Power Window Relay Mod Mystery

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Bowtiek10, May 17, 2017.

  1. Bowtiek10

    Bowtiek10 Registered Member Premium Member

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    Recently I tried to do the standard 4 relay mod for my power windows. Diagram pictured below
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    The issue that is mind boggling to me is that I followed this, (yes I know it says Trans am but the colors are the same, thanks GM) HOWEVER all that happens is that my relays click. No window movement whatsoever. If I put my voltmeter on the plug that goes to the motor, I get 12v. I know for sure the wiring is correct because if I jumper the 86 and 30 pins, which would take me back to the original wiring style, the windows will move for me. The grounds are good too, and they would have to be otherwise my relays wouldn't click. Hoping for the best as the slow windows leave much to be desired.
    Thanks in advance
     
  2. CrpMag122

    CrpMag122 1/2 ton status Premium Member

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    The way they have the hot wire coming in does not make sense to me. The way I see it the power wire coming into the relay should be connected to 30 and power to the motor should be from 87. DO NOT take my word for this though. I am not very good with electrical. I am assuming these are SPST Bosch style relays?
     
  3. CrpMag122

    CrpMag122 1/2 ton status Premium Member

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    I could be wrong, I guess in theory it could work either way. I have always been told to make the hot wire in as 30 and out as 87.
     
  4. 6872xtc

    6872xtc make mine modified Premium Member GMOTM Winner

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    That schematic isn't going to work as is.
    It tells you to run a new chassis ground to the motor. The motor in these trucks have the power and ground switch polarity to change direction.
    If you ground 87A on the relays, it will work. The non- energized relay will provide ground for the motor when the other is energized.

    Test it to make sure that I am correct, and not wacko...
     
  5. JoshHefnerX

    JoshHefnerX 1/2 ton status Premium Member

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    Not sure about the door windows but the tailgate window works like the diagram.
     
  6. 6872xtc

    6872xtc make mine modified Premium Member GMOTM Winner

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    Yeah, the tailgate motor works like that.
     
  7. Bowtiek10

    Bowtiek10 Registered Member Premium Member

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    That's all it took. You are the man
     
    brans87 and 6872xtc like this.
  8. 6872xtc

    6872xtc make mine modified Premium Member GMOTM Winner

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    Glad I could help!!!!
     
  9. 76k5blazerr

    76k5blazerr Git-er-dun Premium Member

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    So did this make your windows faster and stronger? My front windows work fine but my tailgate window is slow and kind of weak. How is that diagram the same for the tailgate window when its only 1 window and that diagram is for 2?
     
  10. Bowtiek10

    Bowtiek10 Registered Member Premium Member

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    It's a night and day difference. The big reason is that I'm running a bigger gauge wire, and there is less voltage drop compared to the 16 gauge OEM. This diagram is for my driver and passenger door, the only difference for you is that you would have less wiring which is a plus, and likely 2 relays in total instead of 4
     
  11. 76k5blazerr

    76k5blazerr Git-er-dun Premium Member

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    Sounds like I need to do it to my back window
     
  12. Blue85

    Blue85 Troll Premium Member

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    The wire colors may be the same, but the motors are different! Several other diagrams have been posted on CK5.
     

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