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I have a 77 C3 Corvette and I am trying to trouble shoot a non-working windshield washer system. I have performed some testing and suspect the problem is a faulty washer switch located inside the steering column but that's not a cheap or easy repair so I want to be certain it's the switch before replacing it. The switch operates properly for the signals & wipers but not activating the washer pump. Here is what I have found so far. The washer pump does operate when I directly connect test positive and ground wires to it. With the ignition "on" there is power at the wire harness connector to the pump. How do I positively conclude if the switch is faulty or not?
Last edited by hogwild4; Feb 20, 2019 at 10:14 AM.
I have a 77 C3 Corvette and I am trying to trouble shoot a non-working windshield washer system. I have performed some testing and suspect the problem is a faulty washer switch located inside the steering column but that's not a cheap or easy repair so I want to be certain it's the switch before replacing it. The switch operates properly for the signals & wipers but not activating the washer pump. Here is what I have found so far. The washer pump does operate when I directly connect test positive and ground wires to it. With the ignition "on" there is power at the wire harness connector to the pump. How do I positively conclude if the switch is faulty or not?
You know the pump operates when you supply power and ground directly to it. Start with this, About halfway down your steering column there will be a flat 4 wire connector disconnect it. On the female end of the connector use a jumper wire one end to a known good ground and the other end to the dark blue wire. With the ignition switch on the pump should run if there are no other disconnects ie bad connection at the bulkhead fuse box connection.
Now, if the pump runs using the above, it could be dirty washer switch contacts, a broken wire at the switch...(I have see this)...
The picture is a 77 wiper switch and the BLOCK red arrow is the stationary contacts and the line red arrow are the spring contacts that move when you push the turn signal arm in.
Funny... I just posted this on my tech site a month ago... You and anyone else should use this site as your go to... If I post it here or anywhere else I'll post it in the tech site.. Here is the link... http://repairs.willcoxcorvette.com/
So... I humbly ask that if you don't mind bump my sale threads...
Willcox
Last edited by Willcox Corvette; Feb 20, 2019 at 10:38 PM.
After testing the continuity per the Wilcox Corvette diagram above here are my findings. I suspect the washer switch is not making the ground connection within the switch?
First I wasn’t sure if the testing was to be performed with the ignition switch on or off so I checked it both ways on & off.
Ignition off: Has continuity between pins 2-3 only.
Ignition on: The diagrams top left, top right & bottom left have the continuity results as the above diagram indicates they should. However the bottom right (wiper switch in the wash position) I get the following continuity results; 1-2, 1-3, 2-3. No continuity from 4 to any others and yet 3 has continuity?
No continuity on pin 4 so I suspect that's indicating no ground being made by the washer switch?
But why is it that pin 3 does have continuity?
I haven't yet but next I will perform the check suggested by bmotojoe.
Last edited by hogwild4; Feb 23, 2019 at 03:50 PM.
Diagnostics are complete thanks to bmotojoe & Wilcox Corvette! bmotojoes test showed that grounding at the terminal block did activate the washer pump and Wilcox test also confirmed that the problem is that the washer switch ground within the steering column is my problem The next thing I guess I'll have to do (if I want the washer to work) is to dig down into the steering column and hope that I can clean some contacts pointed out by bmotojoe or replace the switch. Thanks again for the all the help folks!!!!
I have the same problem as you have in my 77. All features of the wiper switch work correctly except the wash contacts. I expect to find dirty contacts or a broken wire at the switch. I just can't justify tearing the column down for this, not now anyways. I purchased this momentary push switch and mounted it to the speedometer reset cable bracket (there is already a extra hole in bracket). Looped a black wire from one side of the switch with a eyelet connector (3/8") around the threaded shaft of switch. I also pulled a new Dk. Blue wire to the washer pump through the extra room in the speedometer cable grommet at the firewall. Popped out the yellow wire from the plastic housing and landed it on one side of pump motor, landed new Dk.Blue wire on the other side of pump motor. The speedometer reset cable bracket is already grounded by the reset cable so no need for a new ground. Maybe someday I will feel like digging into mine and fixing it correctly, but for now because it's just switching a ground and rarely used its good.
Frys have the switch for about $7.00
Last edited by bmotojoe; Feb 24, 2019 at 04:10 PM.
Diagnostics are complete thanks to bmotojoe & Wilcox Corvette! bmotojoes test showed that grounding at the terminal block did activate the washer pump and Wilcox test also confirmed that the problem is that the washer switch ground within the steering column is my problem The next thing I guess I'll have to do (if I want the washer to work) is to dig down into the steering column and hope that I can clean some contacts pointed out by bmotojoe or replace the switch. Thanks again for the all the help folks!!!!
Glad to be of assistance... You and everyone else got lucky... I had a 77 column extra with a good switch so I decided to test it out before I put it up on the site for sale. It sold in two days.
Now, in most cases you can take the switch out of the column and repair it. The wash circuit is just a simple set of contacts similar to those in a fixed relay. If the pivot isn't broken in the switch you can usually file the contact points with what we call a point file (used on 1953-1974 cars) and file the contacts flat by holding them together while you drag the file through them. You could also use 200 grit sandpaper to accomplish the same results.
How to test windshield washer switch
The next thing I guess I'll have to do (if I want the washer to work) is to dig down into the steering column and hope that I can clean some contacts pointed out by bmotojoe or replace the switch. Thanks again for the all the help folks!!!!
