Need help diagnosing windshield wiper pump not working (1 Viewer)

[MrClean]

Let me just say I'm really, really out of my element when it comes to electrical. Ok, I have a 1979 pickup and I'm trying to figure out why my washer pump is not working when activating the switch. Here is what I have done so far.
- the windshield wipers work on all three settings (intermittent, low, high) so I believe this verifies any fuse problem
- I tested the washer pump by connecting 12 volts straight to the connections on the pump and it runs fine
- using my voltmeter I connected to the terminal connector that plugs into the pump and when I push the washer button, I do not see any voltage on the voltmeter (see below connector pic)

I'm assuming my next step is to test the switch, but here is where I get little lost and need some guidance. Attached is a pic of the FSM and steering column. It looks like I need to unplug the wiring connector on the steering column and then connect my multimeter (on continuity setting) across pins EW and W and then press the washer button. If I get continuity, then my switch is good? If no continuity at switch, is it possible to take it apart and clean? If there is continuity, what's next? Thanks.

 

[gnob]

There should be keyed power to the washer plug. The stalk switch is a ground path..

 

[MrClean]

You'll have to dumb it down for me gnob. I see that same diagram in the FSM. All my tests have been with the key in the on position. Not sure if this matters, but the washer pump is not the original and is just a universal pump/washer tank.

 

[gnob]

There should be 12v on the blue wire at the pump plug.
The blue/white is going to ground through the stalk switch

 

[MrClean]

Ok, with key on and voltmeter connected to negative terminal of battery and blue wire on pump plug I am getting 10.4V. Seems like that should be showing 12V?

 

[msahr]

The stalk works as the ground path for all the functions, wiper as well as washer. You say the wipers work in all functions so likely the ground is good. So yes, test for continuity between W and EW. If you have continuity, switch is good.

Now do a continuity test on the other end of the wire, from the body connector to the washer motor.

Those old connectors are prone to failure. Many of my connections on my '80 have failed and I've had to replace them. If you just want function over originality, just use insulated crimp connectors.

I dont know if you have much experience in this, but I go back a bit and remove the old wire, solder and heat-shrink same color automotive wire to the original spot, and crimp a new connector.

 

[msahr]

Ok, with key on and voltmeter connected to negative terminal of battery and blue wire on pump plug I am getting 10.4V. Seems like that should be showing 12V?

While pushing the washer button? Yes its a little low but old wiring or a bad connector at the washer may cause this. Try to connect to the wire behind the connector as it enters the shell.

 

[MrClean]

No, I am not pushing the washer button. I just have key on and measuring for 12 volts on the blue wire. Key off = 0V, Key on = 10.4 volts checking at front and rear of connector.

 

[gnob]

You should have battery voltage more or less.
Piggyback a ground from the pump to the chassis and check. 10v should turn that motor.
Your switch is probably just dirty

 

[MrClean]

Per your suggestion, gnob, I used the 10V off the plug and connected ground to the other lead on the pump and the pump does work. So I need to check the switch. I can test for continuity or maybe just clean the connections on the stalk switch first. How does that stalk come apart? Does the cap on the end just pop off so you an access the connections? Thanks to the both of you for you help.

 

[gnob]

Ive never pulled one apart. Maybe you can get away with spraying with contact cleaner.

 

[msahr]

I've never pulled one apart either. However I do know from unfortunate experience that the button is just held in by clips on the button itself and there's a spring underneath which reveals the real button. Try the continuity test first.

 

[MrClean]

Well, good news and bad. Good news is that I've diagnosed where the problem is. Bad news is that it is the switch. I tested continuity from the wiring harness (see pic) back to the switch and I have NO continuity when the button is pressed. I then tested continuity from the wiring harness (ground side) back to the washer motor connector and I have continuity there. I tried spraying liberal amounts of contact cleaner in the wiper stalk, but still not working. I really wish I knew how to take this thing apart because I REALLY don't want to destroy it in the process. I would imagine these aren't easy to come by.

 

[gnob]

I might have one of these. Ill dig around tonight or tomorrow.

 

[MrClean]

Thank you sir. Even if you find a broken one, maybe figure out how it comes apart.

 

[msahr]

I might have one of these. Ill dig around tonight or tomorrow.

If you don't I might as well.

 

[msahr]

I looked online and wasn't able to find anything yet about that switch. Plenty of very helpful YouTube videos about changing wiper blades, though.

 

[gnob]

Sorry, no luck

 

[MrClean]

No worries. Thanks for looking. I'll keep an eye out for one. I've never been, but I may take a trip to a salvage yard. Anybody know of any good yards that have these old trucks in the Dallas area?