Wiper motor tips

[mogdobz]

Hello all. I would really appreciate some guidance on my wiper motor. It was previously over eager and ran the wipers on ignition without the switch being on. I tested whether the whole thing was being earthed by removing the earth wire - and this stopped them from working so there is no faulty earth elsewhere. Must be something in the motor. The issue I've got is not knowing much about how it works and is meant to all go together, what should be checked and adjusted, etc. - the Haynes manual has a good cutaway illustration but doesn't really tell me how to get in and assess what might be wrong. Any chance anyone knows where to find some guidance, illustrations, or videos on the wiper motor so I can diagnose the fault?

For clarity, something in the wiper motor is earthing it when it shouldn't. I think...!!

[Bill_qaz]

Most likely the self park is faulty, it should provide earth until wipers reach park position then go open circuit when the switch is off. The wiper switch gives it earth when on to keep wipers running.

Screenshot_20240720-171042_Samsung Internet.jpg (171 KiB) Viewed 3518 times

When the contact gets to the gap it should stop

[mogdobz]

Hello Bill, thank you very much. You are right. In my case there was a bit more to it.

The earth wire going from the commutator had perished. It was making contact at a couple of points along its length. I suppose that explains the wipers going on occasionally when the switch is in the off position.

Took me a while but removed the whole lot and took it to bits. Interesting to see a motor like that! Soldered on a new earth wire and took it back through to the wiper park mechanism cap. Soldered on (after carefully reassembling the motor since the earth wire threads back through the motor housing) to the park system cap and then reassembled and bolted it all back into the car. Soldering it to the park cap was perhaps a bit pointless - it was held on quite handsomely with the loop on the contact anyway. Fiddled with the wipers a bit and now all is well once again.

Anyone finding this in the future could do worse than consulting this website:

https://www.mgaguru.com/mgtech/electric/et113.htm

I also used a couple of videos for reference:

https://youtu.be/Vavs_qu7Au0?si=o9c-mgX_mGwunXxJ

https://youtu.be/P4EfYMv0XHI?si=Wk-Kjda_fDRsLDdR

And the Haynes manual, of course.