We are working on a 1980 Corvette, having issues getting the wiper/washer to work correctly. We have been using the above wiring diagram for diagnosis and troubleshooting.
We tested the motor and found that it needed to be replaced, along with the switch and controller assembly, and we have installed all three of the new pieces. The wipers now work but only on low speed, we nave no high or delayed speeds regardless of what position our switch is in. The wipers do stay in park when turned to the off position.
Our next step will be checking for continuity in the signal wires.
What else could keep the wipers from working properly? Any help would be greatly appreciated, thanks.

 

Did you transfer the old motor cover over to the new motor? The wiper delay covers have a wire connection for the delay function. It is the Pink wire showing on the diagram connected to motor. did you replace the controller behind the passenger seat compartment with a new electronic or original old type/new/used? I replaced mine with an electronic model and it works great and runs cool, not hot like the old original.

Here is a link to another thread with more information and troubleshooting.

https://www.corvetteforum.com/forums...82-wipers.html

 

What a crappy factory schematic! No illustration of switch contacts! I'm looking at my '79 schematic (FAR better) and while the switch and controller have changed the motor itself is the same.

Low-hi speed is accomplished via the 91 circuit. In ever setting EXCEPT "high", the grey wire at the motor should show continuity to ground. There should be NO continuity with the switch at "high". It would not surprise me if you received a bad switch. Even though it is different, the one I ordered for my '79 arrived with the delay resistor in the circuit in every place EXCEPT the "delay" position on the switch--the exact opposite of what it should be! I wound up using my old switch even if it has an occasional problem in the "delay" position.

As Reaper19 said the intermittent feature will NOT WORK without the special cover that has a pink wire coming out of it.

Again there were some changes in both the switch and the delay control between '79 and '80 but the wiper motor itself is the same. Your schematic shows a diode between circuit 92 (purple) and 93 (white) at the motor connection. Such is not present in '79. It almost looks like that diode is installed across the wires at the harness connector. I would be certain that it is both present and functional. Remember--diodes will show near perfect continuity in one direction and extremely high resistance when you reverse the test leads.

 

We reused the old motor cover, with the pink wire, and our controller is a new electronic type. We have both the original and new controller in the car and have tested operation with each plug in and there was no change in operation of the wipers.
We are going to test the wires today, we believe that one of the signal wires is bad but were unsure of exactly which wire it is. We will also test the diode between circuits 92 and 93.
Thanks

 

Am I correct that you have no operation whatsoever with the switch at "hi"? If so then verify that the wiper motor ground is connected. The ground is circuit 150 and routes through connector #403 (not switch #403 as shown on your schematic).

"WIPER MOTOR speed is controlled by the section of the WIPER SWITCH connected to the WIPER MOTOR (91 circuit). The WIPER MOTOR operates at Low speed when its SHUNT FIELD coil is grounded through the 91 circuit. The WIPER MOTOR operates at High speed when its SHUNT FIELD is grounded through the 20 ohm resister located inside the WIPER MOTOR."

At low speed, the switch provides a second path to ground. At high speed that path is closed and ground must come through the 150 circuit.

The wiper motor has ignition power so operation is all about grounding.

You should verify that the grey wire at the motor has continuity to ground in all positions (including "off") EXCEPT high. If it has continuity to ground at "hi" either the switch is bad or the wire is shorted to ground.

Also verify that the purple wire at the motor has continuity to ground at every switch position except "off".

You can verify that the motor is working properly by grounding giving +12V to the white wire at the motor and ground to the black wire. Then ground the purple wire. The motor should run at high speed. Next ground both the purple and grey wires. The motor should run at low speed.

 

On the "hi" speed position the wipers work at low speed. The wipers work on low speed regardless of what position the switch is in (delay,low, or high.) We have also found that the washer pump is bad. Could this cause a problem seeing that the pink delay wire splits off to both the motor and the pump?

 

Did you attempt to "hot wire" the motor in the way I described in the last paragraph? If so and it still only runs at low speed the motor is defective.

The washer not working won't affect the wipers.

 

Yes, we tested it and found that the motor will run on high speed. Last night while testing the continuity of the wires we found that the pink/black wire from the controller to the was open. We traced the problem to the fuse block which was severely gummed up and corroded when pulled apart. After cleaning and bolting the fuse connector back in we now have continuity through that wire and we now have delay speed and wash. After retesting our wires and finding all of the wires have continuity we now believe our switch to be faulty (no high speed) but we will not be replacing it per customer request. Thank you for your insight into our problem, it was much appreciated!

 

I agree that the switch sounds suspect. Again, the replacement wiper switch I received for my '79 did not function properly and I wound up using my original.

 

all those parts went bad at once??? sounds like you have gremlins in that car: crazy: