Hello,
I am trying to get the windshield wipers to work correctly on my son-in-laws recently purchased 1972 vet. The hood has been replaced and the wiper door has been removed. Right now when I turn on the override switch under the steering the wiper come on at low speed and the wiper switch in the dash has no effect what so ever. I don't understand how to get them to work correctly. Please tell me where to start.
Ruken

 

The motor uses a dual field plus a shunt to control the speeds-has a relay inside the console and the motor is powered separately from the actual switch in the dash. I'd watch the videos and do the tests- then we can go from there.

Willcox did a great job document the wiper system- the wiper system are pretty complex...

Here's a test video-


Wiper relay-

 

Hi r,
WELCOME!!!! First Post!
The intent of the wiper arm control switch under the dash panel was to stop the wipers in the 'up' position on the windshield. It's function was to temporarily interrupt power to the wiper motor.
When the wiper door is removed the function of the wiper door limit switch and the plunger must be bypassed. This is one things I'd check in verifying the wiring on your system using the Willcox information.
Good Luck!
Regards,
Alan

The limit switch (left) and plunger (right).

 

Wow Richard beat me to posting my own stuff..

You may have multiple issues here. Since the wiper motor door is missing you won't have the limit switch to kill power on the large red/white stripe wire. So you'll have to look at things a bit differently. I'm sure that this has been bypassed since the motor runs when you turn the **** on.

I think I would start out by making sure the motor will run in both speeds. Do this by removing all wires to the motor... Including the ground.. Then remove the wiper arms from the transmission (we do). Then do the bench test with the motor still in the car and follow the instructions in the video above. Make sure you run all new wires to the motor for testing, this takes the car completely out of the picture.

Go to this link and up load my paper on your system.
http://repairs.willcoxcorvette.com/1...-72-with-test/



Here is how you test the wiper switch.

Willcox Testing a 68-76 Corvette Wiper Motor Switch


Willcox

 

Thanks for the reply, it was helpful. Does the over-ride switch need to be operated before the motor will run. In my case it does but I assume it does. The wiring has really been messed up over the years to make things work.


1972 vet.


Thanks again
ruken

 

Hi r,
No, the switch under the dash is used ONLY to stop the wiper ON the windshield (to change the blades for instance). When the regular wiper switch (on the dash) is moved to OFF, the wipers move down to the 'park' position.
Turned clockwise is it's normal position and the position it should be left in, EXCEPT when it is turned counter clockwise to stop the already running wipers in mid 'sweep'.
Regards,
Alan

 

Thanks I will work on it tomorrow. The switch in the dash has no effect on anything. I bought an new wiper motor, new washer control, and new wiper switch for the dash. The wiring id messed up somewhere.
ruken

 

Slow and easy wins the race................... Don't mess with new.. test what is old first. Saves money and time.

Follow my bench test instructions and then post back. There is enough experience on this forum to figure out any wiper issue. I'll be out of town the next two days but I'll check in...


Willcox

 

This has been helpful but have a similar question. I have a American Auto wire switch and their harness with no wiper door or washer. Any advice to hook it up?

 

Hey Kevin-

shoot me an email and I'll draw one up for you...

richard454@comcast.net

Depending how the American Auto wire does it (more than likely positive switching) a couple relays might be needed.

 

Thanks for the test video

 

According to the video, the wiper motor on a 1972 vet does not run with battery on the yellow lead until either the blue or green is grounded. My motor starts as soon as battery is applied to the yellow without grounding either the blue or green. Am I totally off base or is there a problem with the motor. It is a brand new motor


ruken

 

Why are you totally off base??? The motor is hot all the time waiting for ground (s).. You have a ground issue somewhere for sure because if you didn't the motor wouldn't start.

So.. back to what I originally said.. Remove all wires from the motor.. and remove the arms.. then do a bench test (with the motor in the car) per the video.... This will take the motor out of the equation.

If the motor starts running without grounding the wires out then yes............. you have a motor issue. If not then you know the issue is in the car. If the motor passes the bench test then I'd look hard at the wiper motor relay or the wiper switch and/or the associated wiring.

Willcox

 

Without the motor out of the car, with just the power wire only connected, there is 12 volts on the case. When I ground the case it arcs and the motor will run. What do you think? It is a brand new motor and I did not bench test it before installing. Sorry to be so much trouble.
ruken

 

When the motor runs- is it high speed or low and does it park after you pull the power?

It's not just that simple... there are really three grounds that control the motor- chassis ground-motor field ground (one of the two wires coming out of the base side of the motor) then a shunt or resister to operate the motor in low speed ground. Plus there is a park solenoid switch internally that controls the park function and it has to see 12V and a ground.

You gotta do as like the video for the test....

 

Yes sir, I watched the video again. With battery connected to the main power feed, the case has 12 volts on it without any other lead being connected. When I ground the case there is an arc and the motor begins to run at high speed(the clicking) at high speed. when I remove the ground off the case, it will stop but doesn't park. Thanks for your help, this is driving me crazy. Should there be 12 volts on the case with only the main power lead connedted
ruken

 

I tested the motor again after watching the video. Got the same results! When (on the bench) I connect battery to the main power lead there in 12 volts on the case and 12 volts on the three terminal connectors. When I ground the case the motor begins to run at high speed(just clicks). When I remove ground or power the motor will stop but doesn't park. When I ground the low speed terminal, it will switch to low speed but, when I remove the ground, the motor will go back to high speed. I do not need to ground the center terminal to get it to run. I believe I have a bad motor even though it is new. What are some of your opinions. I do not claim to be an expert. This is the first one I have experienced. I really appreciate all your help.
ruken

 

Alright, so I believe this is what should make the wiper behave. Correct me if I'm wrong.

First, there should always be power and ground to the motor case. This simulates the wiper door open via the override switch.
Then, when the car is on, power is applied to the yellow wire.

When the wiper is off, the green wire is grounded and the blue wire is open (not connected to the ground)
Low speed, both the green and blue wires are grounded.
High speed, just the blue wire is grounded and the green wire is open.

What makes it not work?

If the motor doesn't work at all, then power may not be applied to the motor case and yellow wire or the blue wire between the motor and switch/relay is open.
Only low speed but it does stop? The blue wire between the switch and relay is open. Also, the relay won't click when this happens.
Only high speed but it does stop? Then the black/white wire between the switch and relay is open.
Only high speed and it doesn't stop? The green wire between the motor and relay is open.

If the motor works by applying power/ground manually, then checking the wiper switch and relay is pretty easy.
Then checking wire continuity between the different parts should locate the issue if everything works correctly when tested individually.

Now, it sounds like both your blue and green wires are staying grounded constantly, so I would see where that is happening and it should solve your problem.

 

One thing that may help your thinking on troubleshooting an early 70's wiper problem. It is not a conventional switch that provides power to the motor. The power is already on the motor and the switch in the dash provides the grounds. When you slide the switch to low speed, the switch grounds two wires. When you slide it to high, it grounds one wire. If you look at the switch, you'll see that it has a ground strap to the mounting tab. It is IMPORTANT that the panel you are bolting the switch to is grounded. My wipers did not work and I could put a screwdriver tip between the upper panel where the wiper switch is, and the lower panel where the other gauges are and the switch worked perfectly. I took the upper panel out and added a ground wire from mounting screw that holds the switch to a ground on the lower panel and have had no problem since.

Others here have given the colors that are grounded by the switch and Willcox's video explains the operation well.

 

PS
You can test the operation of the switch with it not mounted by clipping a ground lead from the metal strip on the mounting ear to a good ground in the dash (or anywhere else that's a known ground)