I have a 79 that I am rebuilding this winter. The past owner made a real mess of wiring and other things.

My problem is that the wipers run all the time. The 79 had NON intermittent
wipers, base wipers. Bubba's answer to stop them from running all the time was to cut the white wire (12 Volt + coming from the fuse panel) at the wiper motor and put a toggle switch in series so he could shut off the wipers.

I have done the following checks;
Unplugged the wiper switch in the dash. No Change

Unplugged the wiper motor, with also the dash switch unplugged. I see no short to ground on the Purple or Gray wires.

Then with the wiper motor plug pulled (White, Purple and Gray wires) not attached,. I made a jumper and applied 12 volts ONLY to the white terminal on the wiper motor/transmission socket. The wipers immediately started to run. It appears the there is a short in the wiper motor transmission where the wires attach, providing a ground for the wipers to turn on.

Does my train of thought sound reasonable, or am I missing something.

Thanks
8Valve

 

The motor is hot ALL the time. IIRC Chevy did away w/ relays in 73 on Vettes- the intermittent is a different beast.

There are TWO grounds. The motor has two speeds AKA two field motor using a high and low speed field.

The fields are controlled by the grounds between the fields.

This should help you out-

Willcox has done a GREAT job documenting this stuff!!!

http://repairs.willcoxcorvette.com/1...d-wiper-motor/

 

Right on Richard, no relay and power is on all the time. From your description, one of the fields appears to have gotten internally grounded. I will check out your link. Looks like I pull the motor tomorrow.

Thank You
8Valve

 

1973-1982 Wiper Motor Testing.



1978-1982 Corvette Windshield Wiper Switch Repair
Click on supporting document when you get to this link, a pdf will upload.

 

Many thanks to Willcox for the Wiper Motor test instructions.

This car has been a real headache many electrical circuits. The past owner really molested this car. I have most of the problems now flattened.

Update on the wiper issue.

I pulled the wiper motor out of the 79 today to test per Willcox instruction on my bench. Doing the jumping as instructed, it will run at low and fast speeds. It will not park nor shut down. As soon as you attach 12Volts + to Pin 2 and ground to the case, it starts running. I did find the reason.

On the main output gear is a paw that must enter a set of contact points under the 3 input terminals. The paw does not extend in far enough to open the contact points. The case of the wiper motor has a Reman sticker. The sticker has the following info: "Do not run motor before complete installation is made or reverse polarity will result and motor will jam"

The motor is not jam'ed but the paw portion sure is jammed. I anm not even sure this is the correct motor for a 79 Vette. The mounting holes are correct, the connector is correct as is the output shaft. THe casting number on the motor is
Delco Products, Dayton Ohio, 4960754. I just goolged that number anbd find so far its for Chevy Caprice and Cadillac.

If anyone knows how to un-jam that paw on the large output gear, pleast post.

Paul