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Smart42

Wiper won't return to zero

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Posted (edited) · Report post

My Smart has a new issue: when I turn the wipers to interval the wipers do a half swipe and stop mid windshield rather than returning to rest position. On slow and fast the wipers wipe normally, but when I switch them off they stop right where they are at that moment, not back to the normal rest position. My car has always been garaged and I live in a pretty dry area.

 

I checked:

Wiper linkages:  all intact and I lube them regularly

Wiper stems: get lubed regularly and move freely

Electrical contacts on motor: all clean, no sign of corrosion

Wiring: followed as far as I could, no issues seen

Wiper stalk: disassembled, checked for corroded contact, none seen. cleaned contacts anyway with 1000 grit sandpaper.

SAM unit: no sign of water ingress, all contacts clean, no bad solder joints or signs of overheating on the circuit boards.

 

I tried to find what determines where the wipers are supposed to stop, but have not found it yet. I have a feeling it is in the wiper motor itself, but since they are a pain to get out I thought I ask the expert here if there is anything else I overlooked.

Edited by Smart42

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Don't know if this will help or not:

 

:)

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ive never opened a smart wiper motor and i dont know if the control module is a separate unit but ive seen many gm cars/vans (usually montana/venture) with this problem and its almost always a burned out diode on the control board 

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1 hour ago, jwight said:

Don't know if this will help 

:)

 

Thanks, but no. It is not the position of the wipers on the windshield. When I turn them off they do not return to their rest position. On many cars it could be a faulty wiper relay, but as far as I can tell the relay on the SAM only switches power on and off. Since the wipers do work they are getting power which, to me, indicates the relay is good. Since those things are soldered on to the SAM motherboard swapping them out quickly is not an option.

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Posted (edited) · Report post

Wondering if this is the problem:

 

 

Edited by Smart42
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So update: I removed the wiper motor today. I removed the front panels, disconnected the electric connector and wiper linkage on the arm from the motor. I could not get the nut on the arm off, otherwise I would have taken the arm of the motor shaft. The motor is held in place by 3 bolts. Space is at a premium and a geared flat wrench makes the job much easier. I removed the 2 screws holding the wiper motor bracket to give me a bit more room. With some effort I got the motor out.

Opening the motor required drilling the peened aluminum pins out far enough to wiggle the cover plate loose. Inside you will see the worm drive from the motor itself driving a large plastic wheel with metal tracks. The inside cover has 3 electrical copper contact strips, similar to the ones seen in the video above at 1:45. In my motor the outside strip ( for the parking switch) was broken halfway and the broken part was jammed in the white plastic wheel. Since I did not have another motor handy I removed the broken strip and fabricated a replacement from a strip of aluminum soffit I had laying around. I was able to salvage the old copper contact point and peened this in the end of my home made strip. Put everything back together and had left enough of the aluminum pins securing the cover that I could secure the cover again. 

I was happy to find my wipers working properly again. I do not think my shade tree repair will survive for 14 years like the old one; but it allows me more time to find a replacement.

Anyone with a spare front wiper motor they like to part with?

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