Been working on my '94 vert and getting it back on the road, but lately I've been getting a number of annoying electrical issues. I'm pretty well stumped at this point.

Symptoms - Wipers and washer stopped functioning out of the blue. All fuses are fine, all relays operate normally when supplied with 12V. I wanted to check the Wiper Amp according to page EL-63 of the FSM, but the instructions show a diagram for a 7-pin module, while my green box only has 5 pins. So I didn't mess with that.

Next I tried troubleshooting the Time Control Unit in the footwell according to EL-53. I did the Power Supply Check to start, and everything measured fine for pins 2-15 and 9-15, but measuring across 5-15 shows a very small voltage reading for each Off, Acc, and On. According to the FSM it should read 0, 0, and 12V respectively. FSM just says to "Check harness for TCU power supply circuit", but I really don't know where to go from there.

On Page EL-54 I also did Steps A and B. Measuring across pins 1-15 with the Wiper set to INT should show a swing from 0 to 12V every 3 to 12 seconds, but my multimeter just reads a constant 12V. Step B measured fine.

I have not yet tried putting 12V directly into the wiper or washer motors. Wasn't sure if that would work since there's an Amplifier module.

Is the TCU the problem maybe? Something else entirely? I have no idea if it is related, but my warning chimes also seem to have quit. No longer chimes with the key in the ignition and door open, or with lights on and door open. Finally, the Seat Belt warning light does not come on when unbuckled, even though the seat is plugged in and I've verified the switch is working in the buckle.

'94 is pretty old , an amazing electronics cleaner called De-Oxit can virtually restore the integrity of any contact surfaces like switches and especially connectors . I believe IF you were to disconnect ANY incidental plugs & connectors - spray this stuff ( best into female terminals) plug-in / out couple of times you will virtually guarantee your factory wiring is getting through to the 'devices' . I found it takes a lot of the mystery and intermittent problems out of the equation. I've even , time permits , "fix what's NOT BROKE " by treating many connectors and plugs in the entire general work area , definitely the full circuit I'm on , like from fuse all the way to the grounds ( grounds extremely important) .
In a short time of ownership all my cars and probly 80% of their connectors are treated this way , and I continue to have hardly any weird , intermittent electrical problems , all being simple / straightforward . But I'm retired Union J.W. wireman , and do electronics repairs too .

macgiver wrote: ↑

Thu Sep 02, 2021 10:05 am

an amazing electronics cleaner called De-Oxit can virtually restore the integrity of any contact surfaces like switches and especially connectors

Big +1. DeoxIt is pricey but fabulous, it's our go to for flood- and water-damaged connectors that can't be restored with curettage and WD40. Nobody knows what's actually in the "secret sauce", but it works like gangbusters. It's good for arc-damaged relay contacts too, when you can't get a replacement right away and need to buy some time.

Tried some Deoxit in every connector, no difference

Well ..................................................your connectors are sound now

Also tried a new TCU, still no wipers/washer. I did figure out the warning chime issue, however, as that was a broken wire.

Identifix shows there's a "Wiper Amplifier" under the hood on the firewall, right side if you have ABS or left if you don't. However, the Washer Motor doesn't depend on it, only the wipers do. The Washer Motor is direct-drive through the Wiper Switch. The only things besides the switch itself that look to be common to both are the power and ground wires. You should see power on Lt Green at the Wiper Amplifier, Wiper Motor, and Washer Motor. There should be ground on Black at the Wiper Amplifier and at both Black wires to the Wiper Switch. If you don't see power at Lt Green but fuse F inside the car is good, then there's a break someplace between the fuse and the stuff in the engine box. If you have power, try hooking an external ground jumper to each of the Blacks and see if anything changes. The grounds are in two different places, so check them all. If you find one or both grounds are bad, I'd recommend splicing good grounds to the chassis instead of trying to chase the break.

Keep in mind that it's possible you have two different issues with the Wiper and Washer. To check the washer independently of the wipers, ground the Pink wire at the switch and see if the Washer Motor runs. If it does, most likely the switch is shot. If it doesn't, ground Pink at the Washer Motor. If it runs grounded there, then Pink has a break, if it doesn't, then the Washer Motor is shot.

VStar650CL wrote: ↑

Tue Sep 28, 2021 12:34 pm

Identifix shows there's a "Wiper Amplifier" under the hood on the firewall, right side if you have ABS or left if you don't. However, the Washer Motor doesn't depend on it, only the wipers do. The Washer Motor is direct-drive through the Wiper Switch. The only things besides the switch itself that look to be common to both are the power and ground wires. You should see power on Lt Green at the Wiper Amplifier, Wiper Motor, and Washer Motor. There should be ground on Black at the Wiper Amplifier and at both Black wires to the Wiper Switch. If you don't see power at Lt Green but fuse F inside the car is good, then there's a break someplace between the fuse and the stuff in the engine box. If you have power, try hooking an external ground jumper to each of the Blacks and see if anything changes. The grounds are in two different places, so check them all. If you find one or both grounds are bad, I'd recommend splicing good grounds to the chassis instead of trying to chase the break.

Keep in mind that it's possible you have two different issues with the Wiper and Washer. To check the washer independently of the wipers, ground the Pink wire at the switch and see if the Washer Motor runs. If it does, most likely the switch is shot. If it doesn't, ground Pink at the Washer Motor. If it runs grounded there, then Pink has a break, if it doesn't, then the Washer Motor is shot.

Can I diagnose by unplugging the harness at the Motor/Washer/Amp and running a multimeter between Lt Green wire and ground, or will the harness have to be connected?

Loki wrote: ↑

Thu Oct 28, 2021 6:38 am

Can I diagnose by unplugging the harness at the Motor/Washer/Amp and running a multimeter between Lt Green wire and ground, or will the harness have to be connected?

Yes, you can check it disconnected. In fact, the best way to check it is between the LG and B pins at the connector, if that reads then both power and ground are verified. If it's 0V then check between LG and a chassis ground. If that reads then the ground is bad, if not then the power is bad. You're better off using a bulb-type test lamp than a meter, the circuits all carry power and if it will light a bulb then it will spin a motor. Your voltmeter won't tell you that.