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  1. #1

    Default Power Window help

    Ok, I've read through multiple threads here on power windows, but I am still not quite getting to the cause of my issue.

    I'd never had any window issues in this car (1986 GT Hatch, which I've owned since it was new), but last week my son lowered the passenger window using passenger side switch. I later closed it using the driver side switched, then he opened it again about 15 minutes later. When I went to close it an hour after that it wouldn't respond at all from either the driver side switch or the passenger side switch.

    The driver side window continues to work fine. And the power locks work fine on both doors. I just can't get the passenger window up now.

    Fuse is fine (and I understand if the fuse is the issue then both windows would be dead anyway).

    I removed the passenger door panel and I had an extra window motor, so I plugged it in to the harness. Nothing.

    I used a multimeter to get some readings at the switch and leads going into the window motor:
    • Both of the wires going from the switch to the motor read 11.34v when I press the switch downward
    • Neither of the wires going from the switch to the motor read anything when pressing the switch upward


    So at this point it seems I've ruled out the motor itself, since I plugged in a new one and that didn't do anything either.

    And it seems I know that at least something is happening at the switch (11.34v to the leads going to the motor when switch pressed down)

    But I am not sure that is normal.
    And I am also not sure what (if any) value I should be seeing on the leads to the window motor when I press the switch up? Right now I don't get any value measurement at all when I press the switch up.

    Appreciate any advice you can give.

    Thanks!
    -Eric

  2. #2
    FEP Super Member xctasy's Avatar
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    You are on to it, I think.

    Quote Originally Posted by SECESH View Post
    ..... Electricity is a mystery to most folks, but with a meter you can "see" it, and amaze your friends. If you do get a meter, play with it on circuits that are working to get a feel for how things ought to be. You'll then spot trouble quicker.

    The switches on 12 volt electrical systems have to have better construction than hi voltage 110 or 240 switches. Its probable the switch continuity is the problem, worn from use, the surfacing of the contacts erode more than they do on the internals of house switch for lights, dimmers, fans etc.

    Question you need to answer. If the switch is bypassed, does the window motor work from another closer to 11.9 to 14.7 volt powered source on the car?


    The base voltage after drops due to wiring or partial shorts can be less than the reference voltage at the battery terminals under the hood.

  3. #3
    FEP Senior Member Tigger's Avatar
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    So my question is did you install the other motor or did you just plug it into the door harness? Is the window all the way down? Xctasy is correct, you could use another power source and just hot wire the motor. I use my dewalt battery at times to test things like this with. If it moves then you have a wiring issue.

    I asked about the window being down because the drivers side window randomly gets stuck on my Saleen if I open the window from top to bottom at one shot. When it sticks I have to take the panel off and bang the regulator with a hammer to get it freed. When I just go down hitting the switch 2-3 times it does not stick. I have got used to doing that as I cannot figure out why it does that.

    Hopefully you figure it out.
    67 Mustang Coupe
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    86 Saleen #179

  4. #4
    FEP Senior Member liv2roc's Avatar
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    if I roll my passenger side window all the way down sometimes it will not go back up. I have to remove the door panel loosen the bolts to the motor hit with a hammer and it starts back working. I think it just gets in a bind so I just make sure I dont roll it all the way down.

  5. #5
    FEP Power Member
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    It also takes more effort to make the window go up verses down. Often the crushed safety pins will not work going up but do go down.

    No voltage means itís electrical. Check the schematic, I think the 12 Vdc power comes from the drivers side switch/lock out.
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  6. #6

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    Quote Originally Posted by KevinK View Post
    It also takes more effort to make the window go up verses down. Often the crushed safety pins will not work going up but do go down.

    No voltage means itís electrical. Check the schematic, I think the 12 Vdc power comes from the drivers side switch/lock out.
    Thanks, but to be clear the pink power lead coming into the switch does have constant power whenever the key is turned on.

    And when the passenger window switch is pushed down, both wires going from the switch to the motor register power.

    But when the switch is pushed up, neither wire going from the switch to the motor register power.

    -Eric

  7. #7
    FEP Senior Member liv2roc's Avatar
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    Default wiring

    I dont think both wires should have power at the same time. I think the way it works one wire is negative and one is positive and when you press the up button the positive and negative are reversed and spins the motor in the opposite direction. here is a wiring diagram for an 84 it should be the same as the 86Name:  062.jpg
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    Last edited by liv2roc; 10-09-2019 at 06:21 PM.

  8. #8

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    Quote Originally Posted by liv2roc View Post
    I dont think both wires should have power at the same time. I think the way it works one wire is negative and one is positive and when you press the up button the positive and negative are reversed and spins the motor in the opposite direction. here is a wiring diagram for an 84 it should be the same as the 86Name:  062.jpg
Views: 81
Size:  227.9 KB
    Thanks, this is very helpful. I had another scan of that page but it was barely legible, this one is very clear!

    Ok, so this seems to be pointing to a bad switch module either on the passenger side or the driver side (both being in the passenger window circuit). If it isn't one of those two switch modules, then it could be an actual short in one of the wires in the "push up" path of the circuit I guess.

    Question, so if I jumper 12v directly to one of the leads going into the motor and make sure the other wire has ground, that should drive the motor one direction, right? And switching wires and doing the same should make it go the other way. Would that be correct?
    If so, at least I could do that to 1) see if the motor still works and 2) get my window back up and closed temporarily!

    Thanks again,
    Eric

  9. #9
    FEP Senior Member Tigger's Avatar
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    Quote Originally Posted by eric View Post
    Question, so if I jumper 12v directly to one of the leads going into the motor and make sure the other wire has ground, that should drive the motor one direction, right? And switching wires and doing the same should make it go the other way. Would that be correct?
    If so, at least I could do that to 1) see if the motor still works and 2) get my window back up and closed temporarily!
    Yes, you are correct. You should be able to jump the motor with another 12 volt source. I typically try and use my cordless drill batteries for these types of things but you can use some long wires from your battery as well.
    67 Mustang Coupe
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  10. #10

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    Quote Originally Posted by Tigger View Post
    Yes, you are correct. You should be able to jump the motor with another 12 volt source. I typically try and use my cordless drill batteries for these types of things but you can use some long wires from your battery as well.
    OK, well this really seems to be a switch module issue.

    Here's what I did today... I removed the passenger side window switch module from the switch base, and then I used a short wire to jumper between the power post on the switch module to the post for the Y/R wire that goes to the motor (see picture). Then I plugged the switch module back in to the switch base and turned the key on. The window immediately rolled up as usual with no problem! Then I turned the key off and removed the switch module again. Now at least my window is UP!

    I ordered a new switch module from LMR. Hopefully that's all it needs. Should have it in a day or two.

    Thanks again for all the help here, I feel I am getting really close to fixing this and nice that my window is shut so I can leave the garage again.

    Eric

    Sent from my E6533 using Tapatalk

  11. #11

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    Yep. That was it!! Passenger side switch module was bad. Replaced it and left everything else alone and all is working properly again!

    Thanks again to everyone for the tips and info.

    Eric

    Sent from my E6533 using Tapatalk

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