rear wiper doesn't shut off
 

A question for all you electrical gurus: I recently reinstalled the rear wiper on my '88; it came with it, but I had removed when I switched to a tailless engine lid. Anyway, when I removed it I carefully noted the location of the four wires clipping into the motor. And when I installed it last week it worked fine.

Now today, as I was driving along, the rear wiper started running; flipping the dashboard switch had no effect, nor did shutting off the ignition and removing the key!

When I parked, I pulled off one of the wires to make it stop.

Any ideas?

Wiper motors have power when they are "off" so they can keep going to return to the park position when they are switched off.

Generally this is either an internal issue with the part that supplies the stop interruption or it is a problem with the ground circuit. Check the wiring diagram and see if running a temporary jumper to ground the wiper helps. Note that there two ground connections 31 and 31b. 31 goes to a ground in the engine compartment. 31b goes to the switch.

Have you turned the dial completely off???

Thanks for the replies. The bit about supplying power to the motor so it returns to the park position makes alot of sense.

I don't have a wiring diagram in front of me, but I can check my Bentley manual tonight. Will connections 31 and 31b be obvious? I'm leaning towards something I did in the engine compartment when I either removed or reinstalled the motor. The thing worked fine before.

And, yes, I thought of the intermittent dial too. That was clicked off and yet the wiper still ran.

My 87 did that shortly after I bought it, ran over some rough railway tracks and the rear wiper started on it's own and wouldn't shut off. Pulled and thoroughly cleaned each of the connectors, hasn't happened since.

Start with the simple stuff

Here are a 3 pictures of the rear wiper wiring. Sometimes it is a matter of cleaning the contacts inside the housing.

Off position, no power to motor.
http://forums.pelicanparts.com/uploa...1427810954.jpg

On position, power from switch to motor.
http://forums.pelicanparts.com/uploa...1427810968.jpg

Parked position, contacts bring power from rear fuse, then opens contacts to return to Off.
http://forums.pelicanparts.com/uploa...1427810979.jpg

I did what shrtshck recommended and it seems to have worked. The connectors were rather dirty.

Ed, thanks for those diagrams -- these were actually very clear and easy to understand!