Help troubleshooting power windows

Discussion in 'Sparky's corner' started by brothermo, Oct 15, 2015.

  1. brothermo

    brothermo Well-Known Member

    I just got the dash put back together from a heater core replacement, and I have two separate (I think) electrical issues that have appeared. Here are the two issues:

    1. Voltmeter: Before I put the dash back on, I decided to wire up my voltage gauge. I tied in to the power for the 8-track player for a switched 12 volt supply. Although working initially (for a day or so), this was apparently a mistake as the RADIO fuse has now melted. I intend to put the 8-track power back as I found it and find a different supply for the voltmeter. I was trying for a location that didn't require unbuttoning the instrument cluster/steering column. Any suggestions are appreciated.


    2. Power Windows: These now don't work from any of the switches. Here's what I've done so far to troubleshoot:

    -confirmed power to the battery side of the power window breaker in the fuse box
    -confirmed continuity in the 40 amp circuit breaker

    I would like to check the relay, but I'm not sure exactly what I'm looking at. If I read my service manual correctly, the relay plugs in to the fuse box near the center of the box. I'll try to attach a pic to illustrate. In the pic, I believe the relay is the plug in the center with the two gray wires coming off. Can anyone confirm?

    PA152257.jpg

    The service manual says to check "the output terminal of relay (red/white wire)". Can't see a red/white wire anywhere near the fuse box? Where should I be looking?

    Thanks for any help!
     
  2. GSX 554

    GSX 554 Gold Level Contributor

    Did you check for POWER at both ends of the circuit breaker thats marked Power accy ?? The contacts look pretty rusty from your picture. . Top left of the fuse block .

    Just because the circuit breaker has continuty doesn't mean it can handle the load.
     
  3. brothermo

    brothermo Well-Known Member

    Yes, I have close to 12 volts on both sides of the circuit breaker.
     
  4. GSX 554

    GSX 554 Gold Level Contributor

    What I meant to say was are you testing for power at the circuit breaker or at the contacts in the fuse box ? You can have power accross the circuit breaker and because of the rust and corrosion on the fuse box , which from your pictures it looks like you have a lot of , not have power thru to the fuse box contacts.

    Take the circuit breaker out and clean the contacts of the fuse box shiny clean and see what you come up with.
     
  5. rkammer

    rkammer Gold Level Contributor

    Just connecting a volt meter to the 8 track power lead won't overload the circuit since a volt meter is a very high impedance device. It draws almost no current if it's working right. Somewhere in the process of removing the dash, another short of some kind has appeared.
     
    Last edited: Oct 16, 2015
  6. brothermo

    brothermo Well-Known Member


    Okay, gotcha. I'll shine up the contacts and see where we are. Thanks!
     
  7. brothermo

    brothermo Well-Known Member

    Thanks for the info. I'll pull the dash again and see if I loosened or pinched something the first time around.
     
  8. brothermo

    brothermo Well-Known Member

    Here's the update:

    Circuit breaker is working - power seat runs off of that same breaker, and the seat has been functional throughout this process. I managed to find the orange/black, red/white, and pink wires that run to the power window relay. I couldn't get to the relay without pulling the instrument cluster, but I was able to thread my hand in enough to wiggle the connection and make sure it was snug. Lo and behold, the windows now work. Perhaps I bumped the relay when I was replacing a/c duct hose last week...

    Still chasing down the presumed short on the power to the 8-track/voltmeter...

    Thanks for the tips, and glad to hear any other thoughts on the matter. I'll update again when I've got the voltmeter working.
     
  9. brothermo

    brothermo Well-Known Member

    I had the power windows working. I had the voltmeter working. Never found a short.

    Imagine my dismay when I got everything buttoned back up again this evening, only to find that the 10 amp radio fuse promptly melted. No voltmeter, no power windows.

    Here's my current theory, with a question: I think my short is at the voltmeter body. When I have the positive and negative leads attached and the unit is just clipped up with a clothespin (as it was when I tested it with the dash apart) it works fine (as do the power windows and everything else). When everything is put back together and the gauge is tightened in the bracket, I think something on the positive terminal makes contact with a ground. Possible the cardboard gasket gets crushed to the point of allowing contact. If so, I should be able to remedy that with a thicker gasket.

    So to the question: the inoperability of the power windows has been coincident with the frying of the 10 amp radio fuse. Presumably this fuse is burning out because of a short with the voltmeter setup. Originally I presumed that these events were unrelated, but I think now that they must be. Why would a short on the radio circuit cause problems for the power windows? Very glad for any thoughts on this.:Do No:
     
  10. Drachen

    Drachen Well-Known Member

    I hate to dredge up an old thread, but I too am having issues with my power windows.

    I haven't checked the voltage at the circuit breaker yet (still looking for my voltmeter)
    however everything else electrical works - convertible top, seats, power locks, etc.

    I have checked all the window switches in the car and they are all dead.

    Am I looking at having to replace the power window relay?

    If so, can someone provide me with a part number and where I can find the relay in the car?

    (1970 Wildcat convertible, BTW)

    Thanks
     
  11. Drachen

    Drachen Well-Known Member

    Bump

     

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