Another Wiper topic.

[Dejammey]

My wipers are not working at all on my 76.

I put a test light to the relay and did all the checks that I found on the forum. Everything checked out. Here is the back side of the relay. There is a small burn spot on a weld in the top right but I think that's from manufacturing.

I also put the light to the windshield water pump and it came on too.

Then I cleaned the points where the wiper connects to the harness and put a test light to that and it came on. So then I plugged in another wiper motor to the harness and still nothing.

Now both wiper motors I have are older and could stand a rebuild but before I do that I wanted to bench test the one I have out of the car to see if the motor is the problem.

So this is my question. How do I go about Bench testing the wiper motor out of the car? I have found a bunch of people talking about it but no one has given a step by step how to go about doing it.

I have worked on British cars all my life and had to deal with Lucas all the time but I am starting to feel that the 02 electronics are far more complicated. Well for me anyways.

Thanks guys.

[Mike Self]

Presume both wiper motors you have are "5 wire" motors, not the earlier 3 wire motors. First of all, have you substituted another relay for the one in your car? You can use either a six or seven terminal relay as a substitute--the only difference is that a six terminal relay won't give you the 5 second delay function.

That being said...to bench test the motor out of the car, it appears from the shop manual's wiring diagram that the black wire on the motor is the main hot lead, and of course the brown wire is the ground. Connecting black to positive and brown to negative on a 12v source should make the wiper motor work. All you're testing here is whether the motor is working, not the self-parking mechanism. That's a different can 'o worms altogether.

As for the other wires at the wiper motor, here's how I interpret the wiring diagram: black/white tracer & black/yellow tracer--low and high speed. brown with red tracer: triggers the wipers when the wash switch is energized.

BTW, the wiper motor itself rarely goes bad; it's usually the relay and/or the self-parking mechanism. However, if the latter goes bad, what usually happens is the wipers won't turn off even when the switch is turned off.

Let us know what you find. And let me know if the wire colors are different on your '76. BMW sometimes changed wire colors from year to year, sometimes not...

cheers

mike

[Dejammey]

Presume both wiper motors you have are "5 wire" motors, not the earlier 3 wire motors. First of all, have you substituted another relay for the one in your car? You can use either a six or seven terminal relay as a substitute--the only difference is that a six terminal relay won't give you the 5 second delay function.

That being said...to bench test the motor out of the car, it appears from the shop manual's wiring diagram that the black wire on the motor is the main hot lead, and of course the brown wire is the ground. Connecting black to positive and brown to negative on a 12v source should make the wiper motor work. All you're testing here is whether the motor is working, not the self-parking mechanism. That's a different can 'o worms altogether.

As for the other wires at the wiper motor, here's how I interpret the wiring diagram: black/white tracer & black/yellow tracer--low and high speed. brown with red tracer: triggers the wipers when the wash switch is energized.

BTW, the wiper motor itself rarely goes bad; it's usually the relay and/or the self-parking mechanism. However, if the latter goes bad, what usually happens is the wipers won't turn off even when the switch is turned off.

Let us know what you find. And let me know if the wire colors are different on your '76. BMW sometimes changed wire colors from year to year, sometimes not...

cheers

mike

Thanks Mike,

Figuring out which one was the hot was the main part of my problem. I am going to go grab a relay today and snap it in. I will bench test it tonight and try to take a picture of what mine looks like.

Thanks again for the help.