Power window relay mod/express down

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Matt69olds

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Matt69olds

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Greetings from central Indiana. Long time member, first thread.

I’m doing the power window relay modification to my dads 81 GMC. This was my grandfathers truck, it’s a rusty turd, but been in the family far too long, and has far too many memories to send it to that big scrapyard in the sky. My question, after lots of tinkering, I have determined the express power window down and relay mod are not compatible as explained in the threads. The window relay mod works by itself just fine, but adding the express module causes the window to “chatter” down. I’m assuming I need to isolate the express down module from one of the relays. Any ideas? Thanks
 

Charlie

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Matt69olds

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I figured it out!! However, dummy me left my notes outside in the truck, so I’ll have to update everyone tomorrow. Other than breaking off a couple wires on the passenger side switch connector, it works really well. Got to find either replacement terminals, or a replacement switch pigtail.
 

Matt69olds

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Well, after studying a late 90s C Bonneville service manual, I figured out how to get everything to work. Only issue, I had “express up window”, instead of express down. I figured, no big deal, I’ll reverse the wires at the motor, reversing the polarity. That worked just fine, except the window switch was backwards (pushing the switch up made the window go down). I figured I’d just flip the switch upside down. That works great on the passenger side, however the drivers side also changes which switch controls what window. Time to study the book again!
 

73c20jim

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Try this . . .
 

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rpcraft

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So does the module itself control the stop as well, is that just a resistance load that tells it when to stop? Also does it do auto up as well? I'm looking to set up both doors and the rear for auto up and down and don't want to hand all my money to the nice fellow who builds harnesses for those who can not..
 

Matt69olds

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The module senses current draw, when it senses a big increase in current the module assumes the window has reached the limits of its travel.

I haven’t had much time to fool around with this again. I’m going to attempt to move some wires around in the connector to get the switches to control the windows correctly. Other than that minor issue, the windows move very quickly, and the express down works great.
 

K201979

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What would be your price on a pair of auto down harnesses for a 79 with factory power windows? Thanks
Edit: Pm sent
 
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