Door Lock/Unlock Wiring

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95C1500

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1995 C1500 EC. I ordered a keyless entry system for my truck. Spent the last two weeks
(hour here, hour there) researching, combing through wiring diagrams, etc.. to the point my head hurts. Got it all hooked up and working except for one thing. The actual keyless entry.

Question 1: Are these trucks ground switched or positive switched for door locks?
Question 2: There is no door lock relay in my truck correct? Just in crews/SUV's?

I checked voltage at the connector on the door panel and when "lock/unlock" is pressed, there's voltage.. ~6v. Move own to the driver kickpanel where I tapped the KE harness into the door lock wiring, nothing. Either wire. 0v, before and after the splice.

Door lock/unlock works fine. Hit the switch, both doors react as they should. But no lock/unlock with the fob.

Any suggestions for me? I'm calling it a day for now, have things to do. I'm going to keep thinking about it, retracing my steps, trying to make sense of the wiring diagrams, etc... Just thought someone might have something helpful for me.

Thanks!
 

MSCustoms

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On the 1990 factory wire diagrams the locks are positive switched. Not sure what yours are and the 1990 does not have relays.

Does your keyless entry come with relays?
 

95C1500

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On the 1990 factory wire diagrams the locks are positive switched. Not sure what yours are and the 1990 does not have relays.

Does your keyless entry come with relays?
I figured out they are power switched. The KE system does come with lock/unlock relays, however, a 5 wire door lock set up sounds like what is required. That, and taping into the wires between the switch and the motor which are the wires on the passenger side of the truck. My issue now is I cannot find these wires on the driver side of the truck period. The only place on the passenger side is the door witch itself. From the looks of the wiring diagram, the drivers lock isn't connected to a motor. It looks like the drivers switch passes through the passenger switch which passes through the passenger motor and finally the driver motor to unlock all doors. I'll probably test the system without the 5 wire setup and temporarily tapping into the passenger side wiring to see if that works. If not, I'll attempt to hook up the 5 wire system with the passenger wires. hopefully, the answer lies within one of those tests.
If you go to Hatzie's service manual thread and download the C/K 1995 "Truck" Driveability and Wiring Manual, page 8A-130-2 will have your truck door lock schematic and page 8A-130-9 will have the complete circuit operation description.

https://www.gmt400.com/threads/88-95-service-manuals.43575/
I've got a physical copy sitting in front of me. It is missing 8A-130-9 however.

EDIT: The computer doesn't like the download link. Any chance you have access and could post a screenshot of 8A-130-9?
 

MSCustoms

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That looks like the operation of the 90 schematic as well. It goes from the driver switch to the passenger switch and then to the motors. My keyless entry power came from the truck to the connector at the kick panel, then to the keyless entry box, and then back to the other side of the same kick panel connector. Essentially, the box was bypassing the driver lock switch when the fob was activated but still allowed the lock switch function.

Mine was an old viper alarm with keyless entry and did not have relays. I plan to get a new viper alarm soon. I also still have the box if you need any kind of reference
 

95C1500

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That looks like the operation of the 90 schematic as well. It goes from the driver switch to the passenger switch and then to the motors. My keyless entry power came from the truck to the connector at the kick panel, then to the keyless entry box, and then back to the other side of the same kick panel connector. Essentially, the box was bypassing the driver lock switch when the fob was activated but still allowed the lock switch function.

Mine was an old viper alarm with keyless entry and did not have relays. I plan to get a new viper alarm soon. I also still have the box if you need any kind of reference
Anything would help at this point
 

95C1500

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I figured it out! The LT BLU and WHT wires in the kickpanel were not the right wires. Tapped into the wires by the switch in the door. My truck officially has keyless. Thanks for your help!
 

spinachrat

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I figured it out! The LT BLU and WHT wires in the kickpanel were not the right wires. Tapped into the wires by the switch in the door. My truck officially has keyless. Thanks for your help!
I know it has been a while but which wires did you tap into in the door? The LT BLU and WHT are not working for me either.
 

PlayingWithTBI

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I know it has been a while but which wires did you tap into in the door? The LT BLU and WHT are not working for me either.
On my 88, Grey is unlock and Tan is lock or Lt Blue is unlock and Black/Red is lock, depending on where you cut in. I would think it's the same for yours. Make sure you're using the wires for the door locks and not the windows.
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