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I just replaced my windshield wiper motor. I connected it to the harness, and wallah, nothing. I immediately ran a temporary ground from the a/c compressor bracket, which had it running as expected. I'd like to remove the temporary Bubba ground and I was hoping someone could tell me where the original ground is. Thanks!
From: At my Bar drinking and wrenching in Lafayette Colorado
The wiper motor is always hot in the "IGN" and the "ACC" key positions. It grounds through the wiper switch to turn the motor on. The switch does not provide power to the motor - the switch provides the ground.
Hi Marc,
I believe there's an additional ground needed.
Both the wiper motor and blower motor ground at the same connection near the starter.
Depending on the year of the car it can be on one of the starter mounting bolts or on a bell housing bolt.
Regards,
Alan
Indeed, and more specifically, if I remove the 3 wire connector and put the volt meter on it, I get 12v to the center, and ground continuity to one of the other two, depending on which position the wiper switch is in. However, none of it works unless I ground the motor mount (red circle below) independently.
Originally Posted by lars
The wiper motor is always hot in the "IGN" and the "ACC" key positions. It grounds through the wiper switch to turn the motor on. The switch does not provide power to the motor - the switch provides the ground.
Alan,
Sorry, the car is a '72. The old wiper motor has ground terminal about a inch to the right of the 3 wire connector. If I connect the harness back to that terminal, zero wipers. If I run a Bubba ground, the motor works fine. That tells me that the factory harness ground is disconnected somewhere. Do you know if that specific harness grounds at the starter / blower point you were referring to?
Originally Posted by Alan 71
Hi Marc,
I believe there's an additional ground needed.
Both the wiper motor and blower motor ground at the same connection near the starter.
Depending on the year of the car it can be on one of the starter mounting bolts or on a bell housing bolt.
Regards,
Alan
On the picture you show the copper strap on the bolt that holds the windshied wiper pump to the wiper motor has a spade type connector tab that bolts under the pump bolt. Then you should have a single black wire that connect to it. This is your main ground for the motor and as others have stated I think it runs down to the blower motor then to the starter bolt as Alan shows. In other words the motor housing needs to be grounded for it to work.
If your wiper door is still on the car then you also have a power cutoff switch on the firewall that keeps the wipers from moving before the door is open all the way. Your motor should have a single red wire coming out of the bottom of the wiper motor gear section that goes to this switch.
That should get you started as there are other things that would keep the motor from turning. I just went through my entire wiper motor system including taking my original on completely apart so all of this is fresh in my mind. Let me know if you need additional pictures.
Willcox's video on how the motor works. This helps understand the system a little better and you can bench test your new motor if needed.
The ground for your wipers and blower motor is down by your starter.
TEST the ground wire that you have up by your wiper motor and see if it has 12 volts on it or not. Then see if it has nothing on it and it is a dead wire.
IF it has 12 volts on the ground wire...then someone has put the black wire on the large stud on your solenoid at your starter where your positive battery cable attaches to it.. I have seen this many times.
The wiper motor you have MUST HAVE a wire coming out of the housing that attaches to a 12 gauge red wire.....if you are wanting it to be factory correct. And that is IF your car still has the wiper door in it. IF you no longer have the wiper door...then using a wiper motor for a 1973 to 1982 will work fine.
The wiper motor itself, grounds through the blower motor circuit on your car. The control grounds that operate the motor are grounded thought the switch. The schematic below should help you. Go to this link, there are tons of info on the 1969-1972 wiper motors.
Where does the wiper motor ground?
