Power Window Relay Mod

Discussion in '1973-1987' started by nerfherder78, Feb 12, 2011.

  1. nerfherder78

    nerfherder78 Member

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    I read about this upgrade on ck5.com about 2 years ago and finally got around to trying it this week. I've tried just about everything else: cleaning/lubing tracks, new motors, and even replacing the regulators with new ones from Classic Parts; but this has been by far the biggest improvement. Now my windows go down and up in about 5-6 seconds (with the engine off :eek:)

    Parts List:
    4 SPDT Relays
    ~15 ft Black 12g wire
    ~25 ft Red 12g wire
    2 Inline 12g Fuse Holders & 30 amp fuses
    Wiring Connectors: 20 Female Blade, 12 Ring Terminal, 2 Splices, 2 Butt
    1/4" Heat Shrink Tube

    Relay Wiring:
    85 - power from the window switch
    86 - ground
    87 - power from the junction block
    87a - ground
    30 - to the window motor

    First step was to run 12V to the door, so I ran some 12g wire from the junction block on the firewall to each door (didn't connect to the junction block until I was done, of course). I also ran new grounds from the cab to the doors, just to ensure I had proper ground for the relays.

    Next I placed my relays (2 per window) just in front of the arm rest bracket and connected the hot and grounds. Placing them here puts them in the large void under the arm rest so they're out of the way and downstream of the factory switches, so you have power going directly to the window motor.

    Then I cut the wires in the harness going to the window motor. All you need to watch for here is that you leave enough wire on the switch side to connect them to the relays and to make sure you have the same color wires going to the same relay.

    Last step was to connect the wires at the junction block and test the windows. I also re-cleaned/re-lubed the tracks before re-installing the door panels.
     

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  2. vwnate1

    vwnate1 Member

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    Power Windows

    That looks very nice ! .

    You've taken the load away from the switches too so they'll prolly last forever now .


    FWIW , those #'s on the relays ? they're DIN Spec. and # 30 is for power & # 87 is for the load.....
     
  3. nerfherder78

    nerfherder78 Member

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    Guess I should have mentioned for those that want to try this these are standard Bosch 5 pin/30amp Relays, these are the ones I used.

    You are correct, however the wiring is intentional. If the window motor were hooked up to the 87 pin, then it wouldn't switch to a ground when de-energized and the motor wouldn't have a complete circuit. In this setup, both wires are normally grounds until one relay is energized by the switch and powers the motor in one direction. Activate the other relay and the polarity is reversed, and the motor turns in the opposite direction.
     

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  4. vwnate1

    vwnate1 Member

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    Thanx !

    That's neat .

    I'm no ' Sparky ' , I was just thinking how these relays are used in my beloved German cars....

    I use them to run the electric radiator fan in my truck too , wired live it prevents heat soak in the desert.....
     
  5. Roadhazardguy

    Roadhazardguy Member

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    I did a mod kind of like this the other day to my blazer and now they go up and down in about 2 seconds... I put manuals in. :rolleyes:

    You did a really nice job though! I need to put my headlights on relays like this.
     
  6. vwnate1

    vwnate1 Member

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    Sparky Stuff

    Yes , do that ! it'll not only brighten up the headlights quite a bit , but the headlight & dimmer switches will never wear out again , the battery will charge better & faster , so on and so forth .

    NAPA used to sell a nifty 12 volt dual headlight relay , I've not gone looking for it in many a year tho . in the ECHLIN catalog .

    I was looking at the power wire to my throttle kicker solenoid and ignition coil , a fellow told me to be SURE and use minimum 14 Ga. wire , 12 is better .

    Hmm....... :confused: the FSM says 16 and I used this factory size when I re - wired the entire underhood loom .

    It seems fine but I wonder :confused: .
     
  7. Roadhazardguy

    Roadhazardguy Member

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  8. vwnate1

    vwnate1 Member

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    Heavy Duty ,

    My Patootie ! .

    If it was really heavy duty ,they'd advertise how they're using # 10 Gauge wires...

    I say : buy the cube relays and make your own , use 10 Ga. wire and match the factory color code.......
     
  9. nerfherder78

    nerfherder78 Member

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    I did went from manual to power about 6 years ago and they've been pretty reliable since I swapped in the new regulators, just slow. My pass side window was so slow I thought I might have to replace the motor, but its just as fast as the driver's side now.

    I did this a few years ago as well, but kept most of the factory wiring. Bought new headlight connectors from Kragen (my driver's side was disintegrating) and used 2 of the same relays.
     
  10. Roadhazardguy

    Roadhazardguy Member

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    What do you think about using speaker/amp wire since its supposed to be real low resistance? The blazer has quad headlights so would I still use the same amount of relays but wired to 4 plugs? Wiring seems to be one of my weak points so I might need to be walked through this when the time comes.
     
  11. vwnate1

    vwnate1 Member

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    As Long As

    The current carrying wires are 10Ga. or thinner , you'll be fine .

    Wires come in more or less strands in the same size , more strands means heavier current carrying capability so go _look_ at this speaker wire stuff...
     
  12. nerfherder78

    nerfherder78 Member

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    May have hit my first snag since installing these:

    My driver's side window stopped going up all the way and sounded like the motor was jumping teeth on the regulator. Pulled it apart today, and sure enough, 3 teeth on my regulator had half sheared off. I lucked out and found one in serviceable condition at Pick-n-pull for $20. I replaced both my regulators with brand new ones a few years ago, and I tend to use my pass side window (and d/s vent window) more than the driver's side, so not sure if this was just a random failure or if the motor is now drawing too much power.
     
  13. Chevy1986

    Chevy1986 Member

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    How can you test the motors for windows and door locks to see if the work, i bough doors for m 86 c10 and i got one windows to go up but not down and door locks wont work...
     
  14. nerfherder78

    nerfherder78 Member

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    Do you have the complete wiring harness to go with the doors?
    If you can get your hands on extra connectors for the window motor and lock actuators, you can test them by touching the leads directly to a battery.

    A window going up but not down sounds like a bad switch, pretty common for those to fail. Door lock switches can go bad just as easily, there's also a relay under the dash on the side of the steering column; but I haven't heard of those going bad.
     
  15. Chevy1986

    Chevy1986 Member

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    both windows go up and down,its just the locks tha wont work,but i got the doors from craigslist,so i dont have the complete harness that goes in the cab, i made the widows work with my dewalt battery, so i will need relays to make the locks work?
     
  16. nerfherder78

    nerfherder78 Member

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    The switches activate the lock actuators through the relay. The grey and tan wires in the door harness run to the actuators, if you can touch them to a battery they should activate the locks. Switching the leads will switch from lock to unlock.

    Here's a wiring diagram. Basically each wire ties to its partner from the other door at the relay. The orange and black one also ties into a connector at the fuse panel to draw power, and it appears to ground through the relay.
     

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  17. Chevy1986

    Chevy1986 Member

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    So theres a relay per door lock and windows too?
     
  18. nerfherder78

    nerfherder78 Member

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    Nope, only one door lock relay. Either switch will activate it, and it triggers both locks. The windows don't have relays from the factory.
     
  19. Chevy1986

    Chevy1986 Member

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    Umm ok.. Im gonna go get one :)
     
  20. Chevy1986

    Chevy1986 Member

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    What kind of relay I need?
     

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