what would be a sensible place to start when blindly powering this wiper unit? - Page 1
Forum section: electronics / general

author: twobob
author_rank: Newbie
timestamp: June 07, 2020, 03:00:39 pm
content: hi.I picked up a used VW wiper motor that I want to use for a simple motion experiment.Having no idea how to power the thing I popped open the case and looked inside.Not really wanting to break it (and not being extremely motor savvy) I am asking if my assumptions are correct.A) The large ground looking plane on the left side of the board is likely groundB) The voltage is likely 12V or less. Some of these components look a bit tiny for 12v though?C) The other connections are COMMON +VE, Fast and Slow?I have no idea if any of that is correct or the likely order of the connections based on the diagram. would appreciate any insight on those assumptions.Noting the possible current limiting resistors on two of the channels might this indicate they are the loom switching pins? The center ones?This is just an exercise in guesswork.I did try to find the docs for the part but had no joy. Appreciate any help. I have a limited current power source that I can test out any guesses with. Thanks.I tried asking on Stackexchange but had no joy there.

author: Nusa
author_rank: Super Contributor
timestamp: June 07, 2020, 03:47:45 pm
content: When an automotive part says 12V on it, you generally assume it's intended to function with noisy 12-15V DC power (noisy means high voltage spikes must be tolerated). The so-called 12V power in cars is typically over 14V when the engine is running.I wouldn't make assumption A without more to go on. The right-hand connector could just as easily be ground. If that's a TVS diode on the right side, its polarity might give you a clue.I'd find out what VW models that motor assembly is intended for, and find a wiring loom diagram for one of them. That should give you some clues.Also see if you can find a datasheet for that large IC. You didn't have enough light on the board for the numbers to be legible in the picture.Or you could harvest the motor and use it with your own controller and forget about the original electronics.

author: twobob
author_rank: Newbie
timestamp: June 07, 2020, 03:52:13 pm
content: Thanks. that makes a lot of sense.Did not recognise the diode so yay. that might help.Someone else pointed out that this thing likely has a spray thingy in it for water. and some of it might control that.I'll investigate the diode with a multimeter. superstar. many many thanks. finally something diagnostic to doI did find a very similar picture to this unit here:Also in a manual that may or may not be the exact one it says: Final control diagnosis of onboard supply control unit -J519- The following components can be tested using the final control diagnosis function of the onboard supply control unit ... snip ... "Windscreen and rear window washer pump -V59- , rear" so knowing the output of that blackbox controller appears to be what I am actually attempting to emulate?The chip was a NAGARES 98-0344 did not find a datasheet, just lots of confusing china links to possible distributors?

author: twobob
author_rank: Newbie
timestamp: June 08, 2020, 01:26:08 am
content: Seems like you were right about that not being the ground. Sure looks like VCC to me in that pin one. I am going out on a limb to say that may be their standard.This /should/ be enough to get this going I guess. decades as a musician did not prepare me for electrical nor practical engineering, who knewthanks everyone. tried buzzing out the diode but got an open line both ways?Now I just need to find the exact 20 pin version for mine. seems like there is no sheet online. so that may never happen.

author: Nusa
author_rank: Super Contributor
timestamp: June 08, 2020, 02:55:06 am
content: You'll probably find this interesting:http://www.matthewvaras.com/2014/03/14/2007-audi-a6-avant-rear-wiper-motor-repair/He says that unit runs off a CAN bus (https://en.wikipedia.org/wiki/CAN_bus), which means it's a smart device. To operate it as is, you'd have to know and replicate the signal protocol.That center lead on the motor side is probably a sensor to detect when the wiper is in the park position, so the controller knows when to stop it.If you aren't up to that challenge, you're probably better off replacing that board with your own motor control, however complicated that needs to be. The motor itself is simple.

author: twobob
author_rank: Newbie
timestamp: June 08, 2020, 08:54:20 am
content: yup. you are an absolute superstar. Gigantic joy at this one. many many thanks.Armed with this knowledge I immediately A) learned canbus - no really, spent all night cramming 0bd2 B) realised I could bypass it all and thus did.Gargantuan hugs for the help on this one.I have a moving washer wiper. YAY!!!!!

author: ralphrmartin
author_rank: Frequent Contributor
timestamp: June 08, 2020, 06:54:48 pm
content: Tell you a little story. Back in about the 60s or 70s, a friend of my father's heard about variable speed wipers, and thought they were cool. He designed his own transistor circuit for this purpose, and installed it in his car, under the bonnet next to the wiper motor. He turned the wipers on. There was a tremendous bang, and two round dents in the bonnet. He'd done the calculations for the normal working current of the motor, and had failed to take into account the huge inrush current to get the wipers moving. The dents were caused by the lids being blown off the TO-3 transistors in his circuit...