Car ECU, replace or repair - Page 1
Forum section: electronics / general

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 11:37:54 am
content: Right following on from a very informative discussion about air flow rates into a car engine I have a new problem. My Fiesta MK4 ECU has decided to no longer turn the radiator fan on. I have been to a mechanic and we have checked. He was able to make the fan run by instructing it to via his diagnostics machine and he as I is getting temperature readings from the diagnostics bus. So somewhere in the ECU it has decided to no longer turn the fan on. I am rather perturbed by this as clearly it is not just a blown output transistor as he got it to work via the ecu with manual instruction and the requuired information is coming in. It's like the things programming has changed.I don't know if it is relevant but a few miles prior to this problem being discovered (on being stuck in traffic) my engine suddenly started running more smoothly and with less petrol (I had a few miles back accelerated to 3700 rpm which I rarely do so might of shook some rubbish out somewhere ?). Is it possible that the ecu reprogrammed to account for a change in the engine condition and forgot it has to activate the fan ? or has something burnt out. I am puzzled as the information is going in and it can be made to actuate the fan but it chooses not to.He said I can have it sent away and fixed for about £200, but as this point I wonder, should I just get a new one, it's 12 years old, will anything else in it fail. Or is it a program fault. Educate me on ECU's

author: PeterG
author_rank: Frequent Contributor
timestamp: August 04, 2012, 11:49:21 am
content: Are you 100% sure the ECU controls the cooling fan?In some setups the fan has its own temp switch. If that switch fails the fan wont engage.Regards

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 11:52:32 am
content: yes it does, checked the diagrams and we instructed it to turn the fan on so it definitely controls the fan.

author: PeterG
author_rank: Frequent Contributor
timestamp: August 04, 2012, 11:58:49 am
content: One trick that can fix errors like this is to disconnect the battery for about 24hours. This clears the memory, when you reconnect the battery and start the car it will reset to default settings.Regards

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 11:59:59 am
content: hm worth a try, 24 hours ? that's going to be difficult.

author: PeterG
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:01:20 pm
content: Then again, if the car is running better, just rig up a fan controller and leave the ECU alone......Regards

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 12:03:24 pm
content: my concern is that if it is a physical problem more might go wrong. A good reset should do no more harm. Yes the mechanic suggested I make my own controller.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:04:11 pm
content: At first, i would try to "manually trigger" the the fan. If you already got the schematics, you should know which wire has to be (usually) pulled to ground in order to activate things. BTW: usually it is not the engine ECU which is controlling the fan(s), but if you say so, it may be.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 12:07:12 pm
content: The ecu controls the fan relay. We plugged a diagnostics machine in and told it to run the fan and it did. So I conclude the ecu can actuate the fan if it wants to.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:11:00 pm
content: Ok. Try to activate the relay somehow (without the ecu), if it is working you should check the harness and if that is ok too, it may be the ecu. Also check for the (positive) supply for the fan/relay too (wiring, fuse, etc).

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 12:13:08 pm
content: your not listening, the whole fan actuation circuit works, from the fan right back to the ecu because we made the fan run manually, and whats more we did it through on the diagnostics line of the ecu so even the output stage that actuates the relay works in the ecu.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:15:47 pm
content: Quote from: Simon on August 04, 2012, 12:13:08 pmAh sorry, you're right. I missed that you could start it manually. If the hw is working, no idea then.

author: PeterG
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:17:58 pm
content: Simon,these people may be able to help more.Fiestaguides.co.ukSome info here as well.http://uk.answers.yahoo.com/question/index?qid=20120323060644AAzcEE2Regards

author: Baliszoft
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:18:59 pm
content: How about the engine coolant temp sensor?

author: aargee
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:20:51 pm
content: Sometimes, that fan is controlled by the ECU as well as by a standard temp control loop. The ECU control is for aircon, with the A/C on the ECU triggers the radiator fan at certain (near idle) engine speeds to improve cooling. Not saying this is the case here, but there could be a side by side control for the fan.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 12:22:40 pm
content: Quote from: Baliszoft on August 04, 2012, 12:18:59 pmthat works fine, my permanent diagnostics panel is reading the temp fine. so info is going in, fan can work, but it wont.

author: PeterG
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:22:50 pm
content: Quote from: aargee on August 04, 2012, 12:20:51 pmThis makes more sense to me.Regards

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 12:23:37 pm
content: Quote from: aargee on August 04, 2012, 12:20:51 pmaccording to the schematics the ecu directly controls the fan relay, nothing else. There is no air con on this car and it's the basic model.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 12:24:54 pm
content: Quote from: PeterG on August 04, 2012, 12:22:50 pmThis makes sense if you have air con as the air condenser also needs air throught it from the same fan.

author: PeterG
author_rank: Frequent Contributor
timestamp: August 04, 2012, 12:29:33 pm
content: All i can say is check outhttp://fiestaguides.co.uk/.Someone else must have had this issue at some stage in the last 12 years.Regards

author: G7PSK
author_rank: Super Contributor
timestamp: August 04, 2012, 12:56:03 pm
content: I had a similar problem on a Vauxhall Combo van one hot summers day I got stuck in traffic and found the radiator fan would not work and had to drive home with the heater on to stop the engine boiling. I checked the fan it worked I replaced the sensor switch still no fan when the engine got hot I put both the old and new sensors into boiling water both worked, I heated the sensor while in circuit on the van but not screwed into the radiator the fan came on, so I cleaned out the radiator still no joy so I went the main dealer. I was told that this is a common problem most people don't notice it , It is a design fault the sensor is at the bottom of the radiator not the top and the coolant stratifies leaving hot at the top and cold at the bottom particulary a problem at low revs, slow speeds and with a water pump that is not working correctly. I fitted a new water pump and the fan would come on.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 01:00:42 pm
content: my sensor is in the block, sounds like the radiator was a bad design, should have been a mutipass

author: amyk
author_rank: Super Contributor
timestamp: August 04, 2012, 01:12:13 pm
content: Not so sure how easy it would be to reflash the firmware (or even obtain it) but that would be one way of ruling out firmware corruption, provided it is a flash MCU and not mask ROM/OTP (which is a lot less prone to corruption).The ECU probably has analog circuitry and electrolytic caps, the latter are known to fail.Or it could be something as trivial as a solder joint that's cracked from vibration.Unless the fan output is really directly controlled by the MCU there are other things to go wrong.

author: G7PSK
author_rank: Super Contributor
timestamp: August 04, 2012, 01:23:14 pm
content: Quote from: Simon on August 04, 2012, 01:00:42 pmAre you sure the sensor for the radiator fan is in the block, the one in the block is usually the engine temp. sensor with another in the radiator for fan control as the engine is often hotter than the radiator and with the fan controlled from the engine block you can have it turning on when not required in the winter when the thermostat is keeping the engine hot but the radiator is cold.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 01:26:13 pm
content: Quote from: G7PSK on August 04, 2012, 01:23:14 pmI expect it is near a water channel or pokes into one. the fan control comes from the ecu we know that for certain, there is no other circuitry that I know of that controls it.

author: Balaur
author_rank: Unknown
timestamp: August 04, 2012, 01:29:17 pm
content: Hello,If only you had a Rover or a MG, I would have been able to help you more.The car ECUs are usually well designed and they requires a good knowledge about the specific engine management unit.The decision to turn the fan on is usually made by the ECU on sensor inputs (can be the coolant temperature sensor, or an engine bay temperature sensor) or following an algorithm (car speed vs. coolant temperature vs. external temperature). Effective debugging is only possible if you know the algorithm and you can act on a sensor.Are you sure that there is something wrong with your car? The fan should be on only in specific cases.In any case, the paramount test is to leave the car running while stationary, for a good 20-30 minutes. At some point, the coolant fan should turn on.If the fan always stays off and the coolant temperature starts to be higher than usual, then yes, there is something wrong. Otherwise, I would say that everything is OK.Cheers,Dan

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 01:31:51 pm
content: well we nearly boiled over while in still traffic. I have got the engine coolant to 100C and the fan won't come on.

author: SeanB
author_rank: Super Contributor
timestamp: August 04, 2012, 02:02:04 pm
content: I used to own a Fordza (Mazda badges but ford internals) and they all have a thermoswitch on the left side of the radiator, about half way down. Might be covered with a cowling and hidden by a battery, but is there. Normally it, or the fuse associated with it, fails. Changed a few on assorted Fords over the years, as they are a common failure. SA is a small market, so the UK fordza mechanicals are often used here in the assembly line ( and are exported to the UK as well)so there is most likely a hidden thermoswitch. ask any motor factor, or get the electronic version of Haynes or Chilterns for your model. Otherwise go to an agent and ask at the spares division to look it up on the microfiche. Then grab that 27mm AF spanner and change it.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 02:04:47 pm
content: no electrics on the rad at all. there is not much cowling but for what is built into the square fan.

author: SeanB
author_rank: Super Contributor
timestamp: August 04, 2012, 02:30:42 pm
content: Not even on the sides? If it is built into the ECU then disconnect the battery, turn on the headlights and leave the door open for 15 minutes. This will deplete the keep alive memory capacitor in the EMU and the airbag controller ( lights on and door open is so that there is a resistive load across the unswitched battery bus to make sure) so that they will restart with the default values. Will lose the edaption values, though, so you will need to take a long drive again to relearn them.

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 03:14:27 pm
content: nope no electrics at all. putting sensors into radiators is extra expense and complicates things, the radiator tanks are plastic, very cheap design, we'd buy that rad for about £30 at work, easier to just screw it into the engine. The rad thermostat comes in at 88C and the fan should come on around 98C so some leeway. The fan does not even blow on the whole rad, just half including the area covered by the "shroud"

author: asbokid
author_rank: Regular Contributor
timestamp: August 04, 2012, 03:57:01 pm
content: It would be a good project to get an ECU 'running' on the bench, with all analog sensor inputs to the ECU generated by a microcontroller. We looked at doing this with a Mazda/Ford ECU but after counting 17 sensors, some 10 actuators, and scant documentation on any of them, the idea was soon abandoned!In the Ford/Mazda workshop manual, it was ever so vague.. "sensor X should measure between 0.20v and 1.58v" etc.. e.g. no proper explanation of the role of any of the sensors, their transfer functions, nor how the sampled analog data was actually used by the ECU.The CPU in that particular 1996 Mazda ECU was a 68HC11, an 8-bit microcontroller from Freescale, powered by the Motorola 6800 microprocessor.  The firmware was held in a 256Mbit serial EEPROM. In theory, the firmware could be extracted and run in a processor emulation environment on a PC (in QEMU or similar). ECUs are the quintessential 'black box' device. They have inputs, they have outputs, but what goes on inside remains top-secret!cheers, ahttp://en.wikipedia.org/wiki/Freescale_68HC11http://wiki.qemu.org/Main_Page

author: IanB
author_rank: Super Contributor
timestamp: August 04, 2012, 03:58:45 pm
content: Just read the whole thread. I would think the ECU is the least likely place to look for a fault. It is solid state electronics with no moving parts. There is nothing to go wrong.What you have is a control loop. The engine/coolant temperature is measured in one or more places, this measurement is fed into the ECU, the ECU decides when to turn the fan on.You have verified that the output part of the control loop from the ECU to the fan works OK. But have you verified that the input part from the temperature sensor to the ECU is working correctly? Using the diagnostic computer is there a way to get a readout on the temperature seen by the ECU?One thing I would do is physically check the temperature sensor circuit. Make sure the sensor is working and that all electrical connections are sound between the sensor and the ECU. You could unplug wires and clean terminals with deoxit and/or fine abrasive. Put a meter on the temperature sensor itself and check that it is sending out the right signal.

author: asbokid
author_rank: Regular Contributor
timestamp: August 04, 2012, 04:01:19 pm
content: can you back-probe all the sensors that are used by the ECU to determine fan activation? What is the diagnostic interface like on the Mk.4 Fiesta? Can it diagnose a failed sensor circuit?cheers, aEDIT:ianb(with the funny hair) has pretty much said just that

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 04:52:37 pm
content: I don't know if there are more sensors. The haynes manual was written by two faced bastards who specialize in making things as clear as mud but covering the ground. My book covers 5 models all with different engines. I will have to go though all the partial diagrams and see if i can spot any other sensors. As things stand now the break in the loop is the ECU, it knows the coolant temperature because it is telling me it on the diagnostics line, it can make the fan work if it wants to because we made it do it.I will study the diagrams in detail, see what I can find. Ideally a large printed diagram of the whole car should be included with these books, one per model, the array of partial schematics with details for multiple models is just stupid.

author: asbokid
author_rank: Regular Contributor
timestamp: August 04, 2012, 08:14:33 pm
content: Maybe the coolant temp. sensor worksto a point, so it passes initial tests but fails once the coolant has got hotter?Dunno who produced this manual, but there are some wiring diagrams at the back for the various engines used in the Mk.IV. See page 250 onwards.https://rapidshare.com/#!download|668tl2|362825041|Ford_Fiesta_1995_Service_and_Repair_Manual.pdfEDIT: Or maybe this one?http://thepiratebay.se/torrent/4922665/I'm sure there used to be an official DVD with Ford workshop manuals for most/all Ford models up to 2004, or some such.cheers, a

author: Simon
author_rank: Unknown
timestamp: August 04, 2012, 10:55:41 pm
content: Thanks, will take a look when I'm on a pc. I've gone through the relative schematics in the Haynes manual and can only find 1 coolant temp sensor.

author: aargee
author_rank: Frequent Contributor
timestamp: August 04, 2012, 11:17:53 pm
content: It wouldn't surprise me if the Haynes manual was wrong, especially covering several different versions of your car. All the Haynes manuals I've ever had to look at have always been a let down in the circuit diagram/description area.I think they feel that mechanics don't/can't use this information anyway.

author: Chet T16
author_rank: Frequent Contributor
timestamp: August 04, 2012, 11:27:00 pm
content: Haynes are hit and miss. One copy I have have diagrams that are largely useless while another for a different model not only has accurate diagrams but in them has illustrations of all the connectors.One of my cars has three temp sensors, one for the fan, one for the ecu and one for the dash gauge!

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 01:08:14 am
content: I think Haynes should be ashamed of themselves. They have gone from high quality to con merchantry. Non of their texts make sense anymore or are practical. Clearly not written from hands on experience - bunch of wankers !

author: pickle9000
author_rank: Super Contributor
timestamp: August 05, 2012, 02:45:23 am
content: Hey SimonI had a quick look at the wiring diagrams and there appears to be 2 temp sensors but that of course depends on the engine.I'm guessing thermistors but you'd have to meter them to know for sure. In any case I'd disconnect one then the other and see if you get an engine warning light. You should also be able to ID the one that is for the instrument gauge. I know you had it connected up to a diagnostic tool, did it give the temp of the engine?As for the ecu controlling the fan that is certainly not in the diagram. You could get item 8 in the diagram and wire up the fan in the same way.Regardless of what you do a switch applying power to the fan will keep the motor from getting damaged. Of course you will have to take the place of the computer. I guess that would be a biologically enhanced car. I unfortunately have had several of them (but only until fixed properly)....mike

author: sonicj
author_rank: Frequent Contributor
timestamp: August 05, 2012, 03:30:07 am
content: "The electric cooling fan, mounted behind the radiator, is controlled by a thermostatic switch. At a predetermined coolant temperature, the switch contacts close, thus actuating the fan."If you don't have wires coming off your radiator, well, you should. The ECU needs control of the fan for AC &/or Turbo. Since you don't have either, you could wire the switch directly to the relay (if it isn't like that already). My bet is on a failed radiator thermal switch.http://www.ebay.co.uk/sch/i.html?_nkw=ford+fiesta+radiator+switch-sj

author: dcel
author_rank: Regular Contributor
timestamp: August 05, 2012, 05:58:26 am
content: SimonThere are two temperature sending units in your car, find them. One could be labled as a temp switch, fan switch, or whatever the hell they decided to name it. I have seen those sensors on the coolant return from the radiator, down on the bottom of the engine block, it could be anywhere, you gotta hunt for it.Also look for a BAD GROUNDS, from battery to chassis to engine to dash. After you said that it started running better and then the cooling fan quit, I would really start looking for BAD GROUNDS! Most sensors rely on chassis/engine ground and 5VDC from the ECM to send their signal back to the ECM in a voltage range that it can understand. It is also possible that you have a short to ground or a heavy current draw on that 5VDC line from the ECM. That will create all sorts of strange behavior that is hard to track down. A sensor that is leaky or intermittently shorting to ground or opening up putting 5VDC on the sense line back to the ECU could keep it from knowing when to turn on the engine fan.Check ALL fuses and links with an ohmmeter to insure that they are not blown. Please don't trust any schematic, manual or diagram, they are likely all wrong. Verify by chasing the harness to the very end connectors and make sure there is no pinches, chafing, burns or missing insulation. Change out the cooling fan relay for a known good one, never trust, verify operation or replace it. Automotive environmental conditions are hell on electronics as you know.Good luck...Chris

author: SeanB
author_rank: Super Contributor
timestamp: August 05, 2012, 06:08:32 am
content: Just talked to a mechanic friend of mine, and he reminded me that a lot of those coolant sensors are mounted in plastic blocks inline with the piping for a lot of cars. Look at the plumbing ( you may have to remove a lot of plastic trim covers to see) and look at the water piping for a black object with a connector or two coming from it. Post a photo and WE will be able to ID what the part is.

author: amyk
author_rank: Super Contributor
timestamp: August 05, 2012, 06:45:12 am
content: What's the exact model of car? The 1995 service manual pointed out above does not show any ECU control of the fan.

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 06:48:16 am
content: Fiesta mk4 2000 finesse

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 07:12:24 am
content: Quote from: asbokid on August 04, 2012, 08:14:33 pmPiratebay is blocked in the uk

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 07:16:44 am
content: Quote from: asbokid on August 04, 2012, 08:14:33 pmIt's a sodding Haynes manual and for the MK3 I think. Has no 1.3L but a 1.4L engine and calls it HCS, this was the predecessor and basis of the endura E I have. Probably the same as my dads old ecscort from 1989

author: Wilkins
author_rank: Contributor
timestamp: August 05, 2012, 07:18:26 am
content: I was having all kinds of wierd problems in my bmw with erratic idles and poor fuel economy, i pulled the ecu out on a hunch and cracked it open.It was heavily water damaged, pins shorted on the IC's, corrosion all over the shop, its a testament to the tolerance of errors in the design that the car ran at all.I was able to score a second hand one on ebay for about 70 pounds + 10 pounds postage, a lot of the different models of ecu are shared between makes of cars, you just need to transfer the rom that stores the program for your car from your old one to the new one.So it might just be worth replacing the thing.

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 07:35:15 am
content: the ecu for mine i think does the MK3, 4 and escort MK6. It is I think in the passenger aread behind the facia so should be protected fro water. Where on earth did they put the BMW ecu ?

author: amyk
author_rank: Super Contributor
timestamp: August 05, 2012, 07:49:54 am
content: Many cars have it under the bonnet, usually beside the engine.

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 08:13:11 am
content: Quote from: amyk on August 05, 2012, 07:49:54 ampretty stupid place, haven't forgotten when my dads escort engine flooded because we ran into deep water the ecu would have gone with it, we dried the engine out but an ecu would not have come out well.

author: SeanB
author_rank: Super Contributor
timestamp: August 05, 2012, 08:33:48 am
content: My ECU is on the top side of the engine, if it is flooded the entire engine is full of water.........If you do get another ECU you will need the keys as well, as they have a transponder that is interrogated by the ECU at power up and randomly thereafter. No match no go, unless you leave the power on for 4 hours, when the ECU will go into limp home mode and ignore the key transponder code.

author: aluck
author_rank: Regular Contributor
timestamp: August 05, 2012, 06:56:34 pm
content: Quote from: Simon on August 05, 2012, 07:12:24 amNo problem here, pal. Check your P.M.I can try to find the diagram for your car, but I need the exact year and model, including engine type (i.e. 1.25 16V DHD).Possible causes for that fault:- you have more than one temp sensor, one for dash and one for ECU- you have just one temp sensor; good wiring between dash and sensor, but bad wiring between ECU and sensor- faulty ECU (seen that, been there)Give me your model and we will try to find out about sensors.

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 06:59:55 pm
content: Fiesta finesse, 2000 Endura E engine.

author: aluck
author_rank: Regular Contributor
timestamp: August 05, 2012, 07:03:19 pm
content: Quote from: Simon on August 05, 2012, 06:59:55 pmIs it 1.3 or 1.4 liter model? 1.4 is 16 valve. And what about horsepower?There's a dozen of those engines, sorry...

author: Simon
author_rank: Unknown
timestamp: August 05, 2012, 07:06:07 pm
content: 1.3L I think 60 BHP

author: aluck
author_rank: Regular Contributor
timestamp: August 05, 2012, 07:16:16 pm
content: Quote from: Simon on August 05, 2012, 07:06:07 pmThen it's J4L or J4J engine. Please P.M. your e-mail address - I've got the wiring diagrams for your car.

author: aluck
author_rank: Regular Contributor
timestamp: August 05, 2012, 07:29:29 pm
content: Here's a short troubleshooting guide:- turn ignition on- check the voltage between battery ground and pin 46 of ECU connector. it should be 0 V- check the voltage between battery ground and pin 7 of ECU connector at room temp (20?). it should be 2.9-3.1 V- check the voltage between battery ground and pin 7 of ECU connector at 80?. it should be 0.7-0.9 V- let as know of the result

author: aluck
author_rank: Regular Contributor
timestamp: August 05, 2012, 07:31:48 pm
content: Quote from: Simon on August 05, 2012, 08:13:11 amthat's why 80% of Russian-made vehicles have ECUs inside the cabin, under passenger's feet.doesn't help much, though.

author: SeanB
author_rank: Super Contributor
timestamp: August 05, 2012, 07:36:03 pm
content: Russian vehicles, built cheap and easy to repair. Really good heaters though...... Add as well a rear window demister, so your hands don't get cold pushing it.....

author: aluck
author_rank: Regular Contributor
timestamp: August 05, 2012, 07:57:14 pm
content: Quote from: SeanB on August 05, 2012, 07:36:03 pmThe only one I really like is Lada 4x4http://en.wikipedia.org/wiki/Lada_4x4It's a real beast when offroad. And it's a pain in the butt on the road.

author: IanB
author_rank: Super Contributor
timestamp: August 06, 2012, 12:28:11 am
content: All this reinforcement of "Found On Road Dead" or "Fix Or Repair Daily" is depressing. May I suggest your next car is a Honda?

author: SeanB
author_rank: Super Contributor
timestamp: August 06, 2012, 05:00:57 am
content: I have had a Ford, very nice vehicle and easy to fix. Only time it died on the road I had a spare ignition module ready, known failure, and it was a pirate one anyway, so I had bought 2 for $5 anyhow..

author: aluck
author_rank: Regular Contributor
timestamp: August 06, 2012, 06:20:57 am
content: Quote from: IanB on August 06, 2012, 12:28:11 amWhy not Subaru? Those beasts are insanely reliable. A friend of mine has Honda CR-V, and his wife has Subaru Forester. They live in a desert area, so just one failure can cost you a lot by means of your health and life. He literally calls her car "an ass-saviour".

author: Zad
author_rank: Super Contributor
timestamp: August 06, 2012, 07:17:03 pm
content: Given the number of people I know who have had big problems with recently made Japanese cars, I wouldn't touch them with a bargepole. Much of the reputation of these companies is down to skewed reliability data as they tend to be self-reported in voluntary surveys. What it usually boils down to, is that cars used by retired people who don't drive much are apparently really reliable, and cars used every day to drive across fields are unreliable. Who knew?

author: WorldPowerLabs
author_rank: Regular Contributor
timestamp: August 06, 2012, 09:02:06 pm
content: Quote from: IanB on August 06, 2012, 12:28:11 amI own a Ford and a Lexus (Toyota). My wife owns a Honda. All are from the late 1990s. All have been reliable and mostly trouble-free. Ford is at ~140k miles, Lexus is around 116k, Honda is almost 200k. OEM Parts for the Ford and Honda are pretty inexpensive. Lexus parts are very expensive, though a better deal can be had by finding the Toyota equivalent. Both Ford and Honda have lots of aftermarket repair parts -- Lexus, not so much. The Lexus has had far fewer annoying problems than the other two (except for the stereo -- even with the Nakamichi option, the speakers are crap). The Ford has structural rust; the Lexus and Honda do not. The paint on the Ford is peeling off of the primer (yes, it is the original paint). The clearcoat on the Honda is failing.None of the vehicles requires than $1000/year on average for repair and maintenance, so I'd say that they all do pretty well in that respect.I used to have a Nisssan. That car was great, except for rust! Had one failed starter -- and no other major mechanical issues in 14 years and 198,000 miles.This reminds me of some jokes:What do you call 6 Chevys and a Ford? A junkyard and a ride home!Nine out of 10 Chevys made in the last 10 years are still on the road. The rest made it home.

author: Unknown
author_rank: Unknown
timestamp: August 06, 2012, 09:41:44 pm
content: Quote from: IanB on August 04, 2012, 03:58:45 pmA few years ago I had to use a pic 16f84a to replace the entire indicator system in a Peugeot 206 because of a failed blackbox. I was so angry with the rip-off price of a new box and the fact that there was no documentation that i was determined to make it work. I bypassed the box for the left, right and hazzard switches, then wrote some code to handle the logic; It worked a treat! You could potentially replace the blackbox and the ecu given enough time and effort. It was certainly not worth it for my crappy 206 though but if you had a nice car you might fancy it.

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 08:13:30 am
content: Quote from: jucole on August 06, 2012, 09:41:44 pmIt's not that simple. There are several Russian wizards who make custom-made firmwares for ECUs. It's rather expensive because of all the equipment they use. And it's very complicated, because there is still no reliable scientific model for internal combustion engine. At least half of the parameters in the ECU are not calculated, they are based on experiments on the exact engine. I know several guys who make so-called "chip-tuning". Basically, what they are doing, is they take your car and your ECU and try to get better parameters for ECU firmware. Sometimes they replace the firmware completely. One could get 20-30 hp more after that procedure.

author: Unknown
author_rank: Unknown
timestamp: August 07, 2012, 09:00:47 am
content: Quote from: aluck on August 07, 2012, 08:13:30 amMy crappy Peugeot 206 1.9 D LX, 2000 year plate was pretty simple as there wasn't much to it, a few sensors etc. I got a ecu and blackbox from a scrap yard and ebay for next to nothing and ripped them apart to study them and did a lot of research, but like I say mine was a simple car, but from what you say it appears it's more difficult for more complex systems, the biggest problem for me was lack of documentation.

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 07, 2012, 11:56:14 am
content: if you already have the schematic and yet still unable to figure out whats going on, i suggest bypassing the fan and temp sensor and make your own FCU (fan controller unit). btw, does anybody know or have ECU schematics for toyota wish car 1.8cc 2003 make?

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 12:19:57 pm
content: Quote from: Mechatrommer on August 07, 2012, 11:56:14 amECU schematics? You are dreaming.

author: Unknown
author_rank: Unknown
timestamp: August 07, 2012, 12:31:53 pm
content: Quote from: amyk on August 05, 2012, 07:49:54 amIn the Peugeot 206 I looked at, there was an ECU (blackbox) by the engine and another blackbox under the steering column. The later Blackbox handled all the non-engine related stuff, including the fan, display, light, indicators, odb etc

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 07, 2012, 12:49:53 pm
content: Quote from: aluck on August 07, 2012, 12:19:57 pmcoz i wonder, if i translated it correctly i read people have their car's ecu schematics (fan controller section) in early page.(i havent read all pages through)

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 01:02:29 pm
content: Quote from: Mechatrommer on August 07, 2012, 12:49:53 pmNope. It's vehicle wiring. What's inside ECU - is a well-kept secret. Never seen a full schematics, although there's nothing hi-tech.Some manufacturers even go so far that they order ICs with their's own markings. And instead of original IC name like NE555 you will get something weird like J25. Good luck seeking a datasheet.

author: Balaur
author_rank: Unknown
timestamp: August 07, 2012, 01:06:30 pm
content: Just some (not so relevant) comments:There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU) or Powertrain Control Module (PCM) and other Electronic Control Units boxes.The lesser ECUs will manage auxiliary functions such as ABS, safety features (locking, windows, engine immobilization), suspension (if active), entertainment units, etc.As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.However, I highly doubt that the core functionality of the EMS unit is easy to be tackled at hobbyist level. Not because of the complexity of the task, most EMS are just a processor (with rich input/output features) with its subsystems and adequate output drivers. The EMS reads sensor inputs and drive a lot of actuators according to some pre-programmed Look-Up Tables (Maps). The difficulty resides in the fact that it's impossible to do anything remotely useful if you don't have an understanding of the physics of the engine and the impact of your actions. It's just not feasible. You should have some ways to observe the engine behavior (problems, performance) and counter-measures to highly dangerous situations (engine knocking, blowing, catching fire, etc).There are some "generic" or Aftermarket Engine Management Units, but these are the result of quite expert people working hard.Cheers,Dan

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 07, 2012, 04:51:28 pm
content: Quote from: aluck on August 07, 2012, 01:02:29 pmDepends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.Quote from: aluck on August 07, 2012, 01:02:29 pmNot just markings. ECU vendors use their own ASICs and the CPUs can be also variants that are not available on the free market (e.g. stripped down or advanced versions of generally available base versions).As a side note: hints uttered here like disconnecting the battery for 24h hours are (most probably) pretty much pointless. There are only a few ECUs which use a RAM with permanent supply. Volatile data is usually stored in SRAM and lost within seconds after disconnecting the battery and after the capacitors discharged (which usually doesn't take very long). Nonvolatile data is stored in EEPROM (old school) or flash (typical nowadays) and therefore won't get lost by removing the battery. Besides when removing the battery there is alway a slight chance that the nonvolatile memory gets corrupted, so be careful with this and do it only some minutes after switching off ignition/accessory.If a component is deactivated due to a stored fault this can usually be either cleared by a normal power off cycle (if it's just temporary) or only by means of an OBD2 device (if it's critical). No need to disconnect the battery.Then again, when a critical component like the fan is deactivated due to a electrical fault, chances are that the engine will only run in some kind of limp home mode. But this is vendor specific of course.Anyway I still would suspect that some temperature sensor is defective. Note that there might be multiple temperatures like oil temperature, coolant temperature, engine temperature, air temperature. The fan is usually controlled via the coolant temperature, but you never know what people come up with. Usually a defective sensor should be detected by the ECU and reported via OBD2. Then again, if it's weirdly floating or it's a dumb ECU, it might as well not recognize the sensor defect.

author: Simon
author_rank: Unknown
timestamp: August 07, 2012, 04:57:34 pm
content: it remains a mystery. Will have a poke around with my diagnostics panel later when I'm hoe from my work course. Not sure what it can do though as it's only basic. I'm certainly not in limp home mode, engine is performing better than it ever has with record low fuel consumption. Have driven up to 70mph and high revs (4300 rpm) with no problems.

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 06:12:32 pm
content: Quote from: Balaur on August 07, 2012, 01:06:30 pmWhy do you consider it improper?Quote from: Balaur on August 07, 2012, 01:06:30 pmRepair? Sure. Did that, been there. Sometimes it's damn hard to solder (check out so-called Chip-On-Board type), but I did that.Improve? Doubt it.Duplicate? Next to impossible in terms of equipment and man-hours.

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 06:20:01 pm
content: Quote from: 0xdeadbeef on August 07, 2012, 04:51:28 pmUsually it's just an 8-bit microcontroller running at 16/20 MHz, EEPROM, a couple of MOSFET arrays, and (maybe) ADC. No state-of-the-art fancy ICs, no FPGAs. BTW, never seen an ASIC inside. Did you?

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 06:22:00 pm
content: Quote from: Simon on August 07, 2012, 04:57:34 pmSo, does that mean that you problem with the fan is gone?

author: SeanB
author_rank: Super Contributor
timestamp: August 07, 2012, 06:27:57 pm
content: Post some photos of the engine, with the water piping shown.

author: Simon
author_rank: Unknown
timestamp: August 07, 2012, 06:55:07 pm
content: Quote from: aluck on August 07, 2012, 06:22:00 pmNo not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode, engine couldn't be running better. But as far as I know the ECU won't cut the fan in.

author: Simon
author_rank: Unknown
timestamp: August 07, 2012, 06:57:37 pm
content: Quote from: SeanB on August 07, 2012, 06:27:57 pmnot easy at the moment, what am I looking for ? it's a cheap two pass radiator with plastic tanks and a rather thin core (I've seen air con condensers that thin lol). There are no sensors on the radiator or on the pipework close by, maybe further back I grant you but no sign of them on the diagrams and the fan is definitely activated by the ecu as we did it manually.

author: SeanB
author_rank: Super Contributor
timestamp: August 07, 2012, 07:41:37 pm
content: Normally next to the engine. The locally made vehicles are sufficiently different to the UK ones ( same kent derived indian made engine but modified for the ambient high temps and altitude changes) that the build is totally different. Not the radiator but the engine bay, looking to the back and down, from the sides and from the back looking down.

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 07:46:20 pm
content: Quote from: Simon on August 07, 2012, 06:55:07 pmIf there is no C.E. light, it's definitely not in a limp home.Still waiting for your measurements for fixin' ya car then.

author: Simon
author_rank: Unknown
timestamp: August 07, 2012, 08:34:12 pm
content: Quote from: aluck on August 07, 2012, 07:46:20 pmhopefully this weekend, I don't think the hotel I'm staying at will appreciate me taking my carto bits in their yard or overstaying my welcome

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 07, 2012, 09:03:44 pm
content: Quote from: aluck on August 07, 2012, 06:20:01 pmEven >13 years ago my very first ECU project had a 32bit CPU. The low end stuff was done with 16bit Controllers until a few years ago, but nowadays it's all 32bit, even in the very small three cylinder engines. On the high end side, there's e.g. a 256MHz CPU with nearly 500 pins (BGA) and the next step is dual core. Plenty of ASICs as well of course. More than 10 in one of the bigger projects. Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

author: aluck
author_rank: Regular Contributor
timestamp: August 07, 2012, 10:26:47 pm
content: Quote from: 0xdeadbeef on August 07, 2012, 09:03:44 pmAs far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?

author: Balaur
author_rank: Unknown
timestamp: August 07, 2012, 10:52:49 pm
content: Quote from: aluck on August 07, 2012, 06:12:32 pmBecause (at least in my experience), the ECU name is usually reserved to (lesser) Electronic Control Units, while the Engine box should be always called EMS or PCM.Quote from: aluck on August 07, 2012, 06:12:32 pmExactly my point. I was talking in this context about the (lesser) ECU boxes, while acknowledging in the next paragraph the difficulty of working with EMS boxes.Quote from: aluck on August 07, 2012, 10:26:47 pmThere are several ARM-based products from Samsung. There are automotive chips, in the sense that there are very well equipped with serial and parallel I/Os, watchdogs, counters, DACs, ADCs, PWM, whatever makes sense in the automotive I guess.A few examples are the following:- ARM7TDMI-based: a few S3F4A*** such as S3F4A1HR, S3F4A2FR, etc- Cortex-M3: S3FMA1U, S3FMA1GThe ARM core (and its wonderful JTAG bus) makes the chip instantly familiar to a lot of programmers (software and hardware). You just need to concentrate on the extended I/O features to make them do whatever you want.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: August 07, 2012, 11:05:26 pm
content: Quote from: aluck on August 07, 2012, 10:26:47 pmYes. Dont forget about the siemens c166/167 on 16mhz either. They also used two of these in conjunction for six cylinder engines.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 07, 2012, 11:05:54 pm
content: Quote from: aluck on August 07, 2012, 10:26:47 pmMost if not All ECUs from BMW, Audi, Porsche etc. in the last ~10 years used e.g. TriCore CPUs (TC17xx) from Infineon or Oak/eSys CPUs from Motorola/Freescale. Even before that, the Hitachi SH7055 was used here and there. In the last few years, also a lot of VW/Skoda/Seat ECUs use 32bit ECUs (mostly TriCore, some eSys). Modern GM ECUs use large FSL eSys CPUs as Viper, Copperhead, Mamba and Cobra. At least the larger ones of these CPUs are BGA.

author: aluck
author_rank: Regular Contributor
timestamp: August 08, 2012, 08:15:56 am
content: Quote from: 0xdeadbeef on August 07, 2012, 11:05:54 pmNice! Do you fix or make those?

author: _Sin
author_rank: Regular Contributor
timestamp: August 08, 2012, 08:37:46 am
content: Here's a picture of the internals of an Audi Q5 ECU:I guess it'll be common across the range.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 08, 2012, 10:44:32 am
content: Quote from: aluck on August 08, 2012, 08:15:56 amI work for one of the biggest suppliers, so we develop ECUs (HW and SW).

author: Unknown
author_rank: Unknown
timestamp: August 08, 2012, 11:10:36 am
content: Quote from: 0xdeadbeef on August 08, 2012, 10:44:32 amcool stuff!! - just out of interest how much input protection is there from the sensors etc on early thru to today's ECUs (HW and SW),? are they easy to mess up?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 08, 2012, 02:10:09 pm
content: ECUs are supposed to be more or less idiot-proof. Stuff like reverse polarity, loss of ground and applying battery voltage or ground to every pin without damage is to be expected even for low end stuff.Depending on the level of protection that a customer requires, there might be also ESD protection for CAN etc.However a normal input pin is usually only protected by serial resistor and (CPU internal) clamping diode.Outputs are usually provided by specific ASICs (e.g. fully integrated H-bridge or highside/lowside drivers) which implement full diagnosis (at least open load, short circuit to ground, short circuit to battery) and self protection.Anyway, I don't think the protection strategies changed that much during the last decade. Just the diagnostic capabilities increased a bit due to stricter requirements.On SW side, you can expect that there is very detailed diagnosis available inside the ECU (e.g. also stuck/inplausible values for sensors) and with modern ECUs,the number and detail level of diagnosis reported to external testers has increased quite a bit. But of course, it will be alway a condensed and simplified version of the information available internally.

author: vl400
author_rank: Regular Contributor
timestamp: August 08, 2012, 02:12:55 pm
content: Quote from: 0xdeadbeef on August 07, 2012, 09:03:44 pmGM used 8 bit for many many years, in Oz we had a HC11 variant based ECU and PCM until changing to a Bosch in 2004 on the locally built V6, the same car but with a V8 went to a 32bit 68k Delphi PCM in 2000 after running the same HC11 prior. We first got them in 1988 using a secondary ASIC. From 1994 it controlled engine and trans but on different hardware. It was all US developed hardware and firmware with aussie engineers doing the engine calibration here. Its a simple processor with well written assembly so has been a hacker and DIY users dream, we have added all sorts of stuff to the code.

author: Simon
author_rank: Unknown
timestamp: August 08, 2012, 04:25:11 pm
content: is there any chance that ignition interference can cause issues, the mechanic said he has had some in the past. Not sure if he was referring to ignition wrecking other stuff or the ignition drivers breaking due to the ignition hardware driven. I think for cheapness most stuff is all in one ecu on my car.

author: aluck
author_rank: Regular Contributor
timestamp: August 08, 2012, 06:31:25 pm
content: Quote from: Simon on August 08, 2012, 04:25:11 pmNever saw one. Read about some issues with Ford Mustang's, whose camshaft position sensor had problems due to EMI.

author: Simon
author_rank: Unknown
timestamp: August 08, 2012, 06:56:34 pm
content: I was thinking more damage done by say related back e.m.f. over time or maybe extra strong due to some extra revving ?

author: SeanB
author_rank: Super Contributor
timestamp: August 08, 2012, 07:13:25 pm
content: Not likely, the normal failure mode of the sensors is the sensor dies, not the management unit.

author: Unknown
author_rank: Unknown
timestamp: August 08, 2012, 07:50:40 pm
content: Quote from: aluck on August 05, 2012, 07:29:29 pmI'm quite interested to see what this turns out to be. I'll put my money on either the temp sensor or a bad connection to the ecu box.

author: Simon
author_rank: Unknown
timestamp: August 08, 2012, 08:01:30 pm
content: but the mystery is how can the diagnostics bus be providing a sensor reading if it's broke or the connection is faulty. The only other explanation is a second sensor and control circuit that is totally undocumented while the ecu is perfectly capable of running the fan as we found so that makes no sense...... I'll try and find the sensor when I get back over the weekend, but as the diagnostics bus gives a sensor voltage don't hold your breath on it being the sensor.Does anyone know the cut in temp for the rad fan on a fiesta MK4 1.3L finesse ? I need to run the engine up to that for testing but want to keep as far from engine burn up temperature as possible.

author: aluck
author_rank: Regular Contributor
timestamp: August 08, 2012, 08:41:14 pm
content: Quote from: Simon on August 08, 2012, 08:01:30 pmcan't tell for fiesta, but it's 97-108 C for the majority of cars. of course, it's the coolant temp. engine is up to 3500C inside and on the surface - it depends on the exact place.

author: Simon
author_rank: Unknown
timestamp: August 08, 2012, 08:51:58 pm
content: well I'm talking coolant temp, at 101C the diagnostics says it's overheating but it may be over reacting to save the engine ?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 08, 2012, 09:26:56 pm
content: Dunno about Ford, but usually the fan should kick in at 90-100°C. Let's say around 95°C. 100°C without a fan hints towards a defective thermostat if the fan itself is working via obd.Are you sure the temperature read via obd is really the coolant temperature? This could be also the oil temperature or whatever.If you locate the thermostat for the coolant temperature, you could try to remove it and see if the temperature changes. Or use coolant spray or a heat gun on it and see if the temperature changes.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: August 08, 2012, 10:36:45 pm
content: Or just simply measure resistance.

author: benemorius
author_rank: Regular Contributor
timestamp: August 09, 2012, 04:55:44 am
content: Quote from: Simon on August 08, 2012, 08:01:30 pmThere are most commonly two or more coolant temperature sensors - one for the instrument gauge, one for the ECU, one for an auxiliary cooling fan. The one for the cooling fan is usually a switch that operates one or more fan relays directly, while the others are full range thermistors. The fan can be turned on by either by the temperature switch directly or by the ECU. Very often the only reason that the ECU has an output to the fan relay is to turn the fan on when the aircon is on. Common sense and good practice might suggest that there need only be one sensor for everything, but I haven't ever seen less than two (yet).Wiring diagrams in Haynes and similar manuals are more of a starting point than a complete reference. Even the rest of the manual will have omissions. If you want to know for sure what your car actually has, you have to get out there and look at it. I'd keep looking for another sensor. It ought to be in the radiator or somewhere along the output of it.

author: SeanB
author_rank: Super Contributor
timestamp: August 09, 2012, 05:41:10 am
content: A reason to think there is a thermoswitch while the ECU has a fan output is that the range does include models with an aircon, and the wiring loom is made for the top range then installed, with only the parts omitted for the base model. This is done to keep from having 2 near identical looms in stock on the line, and allows the decision on which spec is needed to be deferred to further down the line to the point where the dashboard in inserted, rather than at the front of the line. Cost of the extra loom is minimal compared to the extra pick bin, stock shelf ( these looms are supplied on a big board neatly folded so they are not stressed during install or storage) and chances for a mixup in production.

author: aluck
author_rank: Regular Contributor
timestamp: August 09, 2012, 07:08:19 am
content: Quote from: 0xdeadbeef on August 08, 2012, 09:26:56 pmon a majority of Russian produced cars the fan kicks in at 103-107C. it's a NORM. and a coolant is kept under pressure to prevent it from boiling.sometimes I think that those car's engineers have a slight form of dementia.

author: Simon
author_rank: Unknown
timestamp: August 09, 2012, 06:40:00 pm
content: I'm guessing that fan cut in temperature is usually about the same temp above the thermostat opening temp, so with 88-90 degree thermostat opening where does that put fan cut in ?

author: aluck
author_rank: Regular Contributor
timestamp: August 09, 2012, 07:14:35 pm
content: Quote from: Simon on August 09, 2012, 06:40:00 pmUsually that's a different temperature. AFAIR, thermostat opens at 60-70C.I was wrong. It's about the same temp.

author: Simon
author_rank: Unknown
timestamp: August 09, 2012, 08:00:16 pm
content: yea my thermostat opens at about 88-92C and then the temp stabilizes around 85-89C, so much cut in by 98C ?

author: aluck
author_rank: Regular Contributor
timestamp: August 09, 2012, 08:40:09 pm
content: Quote from: Simon on August 09, 2012, 08:00:16 pmif you are in a traffic jam, just opening thermostat is not enough, and temperature will go higher. then the fan will cut in.

author: ot1
author_rank: Contributor
timestamp: August 23, 2012, 04:21:12 am
content: @Simon,I only read part of this thread, but I would say that the ECU is NOT the problem.I would guess its a temp sensor. get the OEM electrical schematics for your car AND THE CORRECT YEAR!!, do not use Chilton or Haynes, they are super crap, full of mistakes and very abbreviated, unreliable for electrical truobleshooting.Many cars do have two water temp sensors check for this.With your friend's OBD tool get into the car's realtime data, read the coolant temp, run the engine and watch the temp climb on the tool and pull the wire off the sensor, notice the change, if it doesn't the sensor is bad. Two wires are probably in the sensor connector, one is ground, (brown?) jumper the connector, read the temp.It is possible there is another control loop outside of the ECU control. You can understand this by looking at the fan relay, for additional connections to the relay coil.you can obtain OEM manuals from Ebay inexpensively, on DVD. Don't buy just the schematics, because they may not be of your car, but with the whole manual to read, you will know.Get on a forum for your car and see if they can help too.