Killing Power Window Switches?

Joined
Jan 30, 2022
Messages
17
Location
Brisbane, Australia
When I bought my 80 a few months ago, the front passenger windows went down a bit, then up then stopped. I though it might have just been jammed, so I went through the process of diagnosing and trying to fix the issue. In the end, I found that the switch had failed and I ordered a replacement.

I wasn't too shocked about that. Its a 25 year old moving part. Things fail.

Problem is, I've just had the same thing happen again with the new switch. I don't know if I just happened to get a bad replacement, or if there's some weird electrical thing going on thats killing my switches on that door. I'm don't know much about electrics, so I thought I'd ask here before buying another switch and hoping it doesn't happen again.

Does anyone have any ideas for things that I could check to see if there's a problem or if its just bad luck?

Cheers.
 
Joined
Mar 15, 2021
Messages
98
Location
Richmond, VA
Did you use a voltmeter to test it and make sure it’s definitely the switch? Might be a matter of replacing the window run channel which is known to get so crusty that the friction is too much for the window motor.
 
Joined
Jan 30, 2022
Messages
17
Location
Brisbane, Australia
Did you use a voltmeter to test it and make sure it’s definitely the switch? Might be a matter of replacing the window run channel which is known to get so crusty that the friction is too much for the window motor.
I didn't use a voltmeter when I was testing it, I didn't have one on hand.

I ended up using some jumper wires to power the motor and it moved up and down just fine, so I tried a switch from one of the other windows.

When it failed the second time, I also tested with another switch and it worked fine as well. I haven't left one of the other switches connected in case there was something damaging those switches.
 
Joined
Mar 15, 2021
Messages
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Location
Richmond, VA
I didn't use a voltmeter when I was testing it, I didn't have one on hand.

I ended up using some jumper wires to power the motor and it moved up and down just fine, so I tried a switch from one of the other windows.

When it failed the second time, I also tested with another switch and it worked fine as well. I haven't left one of the other switches connected in case there was something damaging those switches.
Smart. Sorry for forcing you to write out your troubleshooting. When you say the switch failed- did you replace just the rocker switch or the whole assembly that fits into the arm rest? Might be your connecting wires if the other switch assemblies in the car are able to operate the motor. I am no electrician or expert either. Just a dude drinking his coffee and handing out unsolicited advice on the internet!
 

jellis

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Apr 29, 2011
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243
Location
Boulder, Utah
You definitely NEED a voltmeter to properly diagnose this system, and the EWD. I bought a crappy aftermarket switch on Amazon and it caused hours of headache because the new switch at that window would work but not the master....."Wait what is my master bad?!?!?" I took apart the harness connectors and verified resistance and voltage at the correct pins, everything checked out OK....."Wait how is this possible that nothing is wrong?!?!?" It turns out that the design of the switches is such that if the switch at the window has too high an internal resistance (still has "continuity" but a much-more-than-zero resistance) then it can cause the master switch to not work. A bit of a tricky system to troubleshoot.
 
Joined
Jan 30, 2022
Messages
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Location
Brisbane, Australia
Smart. Sorry for forcing you to write out your troubleshooting. When you say the switch failed- did you replace just the rocker switch or the whole assembly that fits into the arm rest? Might be your connecting wires if the other switch assemblies in the car are able to operate the motor. I am no electrician or expert either. Just a dude drinking his coffee and handing out unsolicited advice on the internet!
I just replaced the rocker switch. Could be something in the wiring from the switch to the motor. Maybe a wire has rubbed through and is shorting out. I'll have to check that.

The other switches I tried were just the rocker switches, not any of the connecting wires. Could be that the position I held them in wasn't causing a problem if it's the connecting wires.
 
Joined
Jan 20, 2013
Messages
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Bay Area, Ca.
A bit of a tricky system to troubleshoot.
Sometimes the trickiest part can be deciphering the EWD.

Once you filter out the minutia, the circuit simplifies to this:

Power Windows.JPG
 
Joined
Jan 30, 2022
Messages
17
Location
Brisbane, Australia
Sometimes the trickiest part can be deciphering the EWD.

Once you filter out the minutia, the circuit simplifies to this:

View attachment 3006370
I managed to mostly work that out. The switch just connects one side of the motor to 12v and the other to ground. Didn't know that it was grounded through the master switch, but I knew they had to both be connected for either to work.

The fault lies somewhere in the circuit after the master switch, because it doesn't work either, going up or down. Either the switch itself is at fault or there's a bad connection somewhere.
 

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