Is the car remote lock/unlock's electronics particularly prone to early failure? - Page 1
Forum section: electronics / general

author: Rick Law
author_rank: Super Contributor
timestamp: May 21, 2017, 10:25:11 pm
content: Is there any thing particular with car remote key lock/unlock electronics that is prone to early failure?Both my car (BMW) and my wife's car (Honda) are >10 yrs old. Both remote car unlock/lock works only intermittently. The remotes' battery is not the issue since they were new and contacts cleaned. I've considered that perhaps besides the battery in the remote switch itself, there may be a battery in the car's receiving end (such as to store the car<->remote pairing information). I've asked a BMW tech and he said no.Well, car is old, and I left it at that.After leaving the matter for a long time. I was at the car repair shop putting on new tires. While waiting, a customer stopped by for remote car unlock switch not working. She was describing exactly the same symptom. I heard the service manager telling that customer that those remote car unlock fails a lot...That made me wonder, if this is just my experience that is less common in the general population, or, is there some particular electronics in the remote lock/unlock that is particularly prone to early failure?

author: xrunner
author_rank: Super Contributor
timestamp: May 21, 2017, 10:31:04 pm
content: I've had similar issues and the culprit is usually the contacts under the rubber keys. Clean the blackish part under the rubber key and make sure the copper is clean on the board. If it still doesn't work order a replacement (which are cheap on Ebay) and just steal the rubber key pad and put it into the electronics part that is already working with your car.

author: rstofer
author_rank: Super Contributor
timestamp: May 21, 2017, 10:32:05 pm
content: We had a Chevy Silverado truck for about 20 years with no issues other than battery replacment.

author: stj
author_rank: Super Contributor
timestamp: May 21, 2017, 11:25:24 pm
content: it could also be interference.there is far too much junk using 433MHz and only 69 channels to use. (most car systems cant use the whole range - transponders are usually fixed to a single channel)far too many stupid people with desktop computers using wireless keyboards & mice for example.why? the keyboard and mouse are right next to the computer!!

author: JPortici
author_rank: Super Contributor
timestamp: May 22, 2017, 07:55:26 pm
content: Quote from: stj on May 21, 2017, 11:25:24 pmeh, all those wires are a mess.sometimes my computer is mirroring screen to the tvbluetooth keyboards/mice are way overpriced in comparison and/or are complete garbage, like apple ones

author: james_s
author_rank: Super Contributor
timestamp: May 22, 2017, 08:10:23 pm
content: I've had to fix the remote for my partner's Prius a couple times now. Crud gets in the button in the fob, it's not all that surprising, these things have a rough life spent bouncing around with other objects in pockets and purses.

author: bitseeker
author_rank: Super Contributor
timestamp: May 23, 2017, 12:24:38 am
content: I haven't had electronics failures in the remotes for the last three cars I've owned that had them: 10, 13 and 17 years old. The button covers can wear out and once one of the cars forgot the code for one of its remotes (just had to resync it), but the electronics have been 100% reliable. YMMV

author: Gribo
author_rank: Frequent Contributor
timestamp: May 23, 2017, 01:09:44 am
content: Most keyboards and mice use the 2.4GHz range these days (It is a global license free band, 433MHz is not). I usually solder some micro switches instead of those dome or carbon switches.

author: Zbig
author_rank: Frequent Contributor
timestamp: May 23, 2017, 10:01:13 am
content: Quote from: stj on May 21, 2017, 11:25:24 pmTesla avatar to show how "special" you are: CheckInsulting people just because they don't like to get tangled in wires that catch on something every time you want to move the damn thing like you do: CheckNot really knowing what you're talking about (keyboards and mice don't use 433 MHz since ages): CheckDouchebag detected. Shit list updated

author: stj
author_rank: Super Contributor
timestamp: May 23, 2017, 01:49:22 pm
content: some cheap ones still use LPD band.get yourself a scanner and see just how much "noise" is out there!dont forget your homeplug network adapters!

author: Jeroen3
author_rank: Super Contributor
timestamp: May 23, 2017, 02:04:01 pm
content: Quote from: james_s on May 22, 2017, 08:10:23 pmKeyfobs are abused. They are in sweaty pockets, purses, thrown onto tables, dropped on floors.Would drift in their clocks make the transmitter and receiver mismatch over time?

author: dimkasta
author_rank: Regular Contributor
timestamp: May 23, 2017, 02:05:05 pm
content: I wouldn't go as far as grouping all car remotes together as prone to failure. Different devices, different builds, different budgets, different environments.I never had any issues on any of mine.My action plan would include a good cleaning of all contacts and a fresh battery from a decent manufacturer.

author: Zbig
author_rank: Frequent Contributor
timestamp: May 23, 2017, 02:38:38 pm
content: Fiddling with the remote and pressing the button repeatedly out of the transmitter's range should also be added to the possible abuses. I've seen people doing that, not realizing that there are only so many steps forward of the rolling code the car's receiver will try to match against until it gives up and assumes it's not the valid remote.

author: Urs42
author_rank: Unknown
timestamp: May 23, 2017, 02:53:09 pm
content: The keyless system in my nissan does not work at the local vehicle inspection station. I couldn't start the motor without using the emergency key. It did work again after leaving the station, and luckily the car did pass the inspection without a working key. No idea what they are running there on the 433MHz Band in this Building...

author: stj
author_rank: Super Contributor
timestamp: May 23, 2017, 03:03:40 pm
content: you are lucky, if the source had been more powerfull then it could have blocked the signal between the induction-loop and the transponder in the key.then your imobiliser would have stayed on!i have a programable radio that can detect & jam those over atleast 100m!!

author: schmitt trigger
author_rank: Super Contributor
timestamp: May 23, 2017, 03:40:18 pm
content: My two yen on the subject:I personally worked with keyfobs and receivers for one of the "Big Three" Detroit automakers in the late 90s.This particular receiver device, which BTW was used on their flagship models, had the tuning achieved with an LC circuit, in which the capacitor was a X7R ceramic.You read that right.X7R ceramic.With all its temperature drifting and aging issues.The receiver was a Philips one, and their app notes indicated the LC circuit tuning, albeit they indicated a N25 capacitor (to compensate for the inductor's drift with temperature).Low receiver sensitivity, specially in cold winter days, was the #1 cause for field returns for this module, which not only had the remote transceiver but also a CANbus multiplexer and other supervisory circuits..Now....this was with a single manufacturer 20 years ago. I ignore whether other manufacturers at the time had similar circuits, or whether this practice continues today.

author: richnormand
author_rank: Unknown
timestamp: May 23, 2017, 10:24:35 pm
content: Had an intermittent issue with the two Subaru keyfob in winter and it was getting worse.Even in summer by then.Car is ten years old and the keyfobs had been working well until about two or three years ago.My wife got the battery changed on hers and it solved it for about 2 months.The spectrum analyser confirmed it was transmitting occasionally but not always.... no frequency drift or rotating codes issue. (Put it in the freezer)It was either on or not transmitting. Cold batteries check out OK too.Took it apart to check for the usual culprits such as bad contacts, broken rubber water shield leading to corrosion, bad switch etc... all tested OK.Even removed the muRata RO3101E resonator (photo) and checked the RF transistor. Then I noticed it was dependent on the battery and the length of wire to it that I was using on the bench.Although both button batteries tested OK for voltage at the rated current one was a brand name and several others some cheap replacement. The brand named one was almost always OK.Solution: the oscillator circuit has the resonator at the base of the RF transistor and relies on a good RF ground to start at the right frequency. So I put a small smd capacitor across the battery circuit near it and both keyfob now work well.Looks like the cheap batteries had either too large an inductance/internal resistance or look like a too small capacitance to provide a good RF ground... no problem since then, even with the cheap batteries.Hope this helps someone as the dealer price for these keyfobs is pretty ridiculous....

author: Halcyon
author_rank: Unknown
timestamp: May 24, 2017, 10:01:45 am
content: Of all the vehicles I've owned with central locking (all being either Toyota or Volvo since 1994 onwards) never had I had a "failure" of the remote central locking system.The only issue I currently have is if I keep my phone (which has a metal rear cover) in the same pocket as my car key, intermittently the key less entry won't detect the key. Without any kind of testing other than keeping the key in my other pocket, I put it down to the phone/metal cover attenuating the signal.I've never had an actual key fob fail, they have all been rather robust and very resistant to dust and water ingress.I've even driven my car to the top of Mount Wellington (Tasmania) and Black Mountain (ACT) where there are signs warning drivers that the transmitter towers on the top of those peaks may cause malfunctions with RF car keys and have never had an issue.