Wiper motor electrical problem
#1 _bangbang_
Posted 10 December 2011 - 11:18 AM
I have recently restored my engine bay in my 1977 LX 4 door, and while I was at it I pulled the wiper motor apart to clean it and re-paint it etc. I put it all back together, and now its doing some crazy shit!! When the ignition is on, but the wiper switch is off, the wipers are operating! Although they pause for around .5 of a second at the end of each cycle. Low and high work as per normal. I have put a volt meter on them, and when they are off the motor is recieving the 12v.
I have also ran a earth wire from the battery direct to the brass earth lead on the wiper motor, but that didn't help. When this problem is happening, the plug on the motor is getting really hot - very quickly.. although this stops when you turn the switch onto low or high.
Any ideas please? Do you think it could be the switch?? Many thanks
#2
Posted 10 December 2011 - 11:46 AM
The park circuit of the wiper motor requires the friction of the wiper blades to stop the motor. The park section is a small area where the park circuit is dead. Without the friction of the wipers the motor will slow down over the dead park section but have enough momentum to make it over the dead park section and then speed up in the park circuit.
Edited by ls2lxhatch, 10 December 2011 - 11:48 AM.
#3 _ss kustomz_
Posted 10 December 2011 - 04:43 PM
#4 _bangbang_
Posted 11 December 2011 - 01:58 PM
#5 _LSLX_
Posted 06 July 2021 - 08:32 PM
#6
Posted 07 July 2021 - 11:18 AM
The wiper switch works by earthing a circuit to make it work.
When the switch is off, an internal circuit keeps an earth on the motor to let it return to its parking spot.
If the wires to this part of the circuit are wrong, it will cause an almost short circuit, which will cause the wiring to heat up and an eventual fuse blow.
A fault inside the wiper motor itself could cause a similar issue.
Check that the wiring is correct first.
The wiring diagram on here should help with colours and positions in plugs.
Make sure the switch itself has a good earth.
Then if no result with that, pull the cover off the motor and check for broken bits and obvious damage.
If you want to play with electrics, Jaycar have a great multimeter/clamp current meter that works on AC and DC.
It is a great tool for finding electrical problems in cars.
Last time I bought one it was about 80 bucks or so.
Better than the 500 to a grand for a name branded meter.
Cheers
Rob
#7
Posted 07 July 2021 - 12:51 PM
Its usually the park contact thats broken. 1st place to start looking anyways.
#8 _LSLX_
Posted 07 July 2021 - 07:00 PM
Ive pulled my motor apart 15 times. Everything is perfect inside. I even hard wired it with my own wiring and still no good. While in park mode it appears to be shorting...if no load (wipers) are on sometimes it will slowly move through the park section. If wipers are on it will blow the fuse instantly in the park section of the cog. I checked to see if 12v is leaking through to sw3 or sw1 but nothing
#9 _Wozz_
Posted 10 October 2021 - 06:33 PM
#10
Posted 11 October 2021 - 10:15 AM
Depending on how the park switching is configured, if you have the wires in the wrong places, particularly when bench testing, you may inadvertently cause a short and it could let the smoke out of the fuse.
Remember that the wiper motor is normally connected with a constant power source from the ignition feed, and earthing the terminals via the switch makes it do its various functions.
The wiring diagram should help with working that out.
Cheers
Rob
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