Wiper/washer quit and other electrical issues

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Loki
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Car: 1994 240SX Convertible
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Wiper/washer quit and other electrical issues

Postby Loki » Thu Sep 02, 2021 7:49 am

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.


macgiver
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Re: Wiper/washer quit and other electrical issues

Postby macgiver » Thu Sep 02, 2021 10:05 am

'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 .

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VStar650CL
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Re: Wiper/washer quit and other electrical issues

Postby VStar650CL » Thu Sep 02, 2021 2:03 pm

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.

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Loki
Posts: 7651
Joined: Sun Oct 15, 2006 7:27 am
Car: 1994 240SX Convertible
2010 FJ Cruiser
2001 SVT Lightning
Location: Detroit, MI
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Re: Wiper/washer quit and other electrical issues

Postby Loki » Tue Sep 14, 2021 4:17 am

Tried some Deoxit in every connector, no difference :(

macgiver
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Joined: Wed Jul 04, 2007 10:21 am

Re: Wiper/washer quit and other electrical issues

Postby macgiver » Tue Sep 14, 2021 12:22 pm

Well ..................................................your connectors are sound now :gapteeth:


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