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Wiring For 7-Way Connector on 2004 Chevrolet Silverado 2500


Truck was wired later, it does not have the white wire for ground, but has red and black wire. Is the black your ground and red for 12 volt charging?


Expert Reply:

On your 2004 Chevrolet Silverado 2500 the factory wires should be light green, dark green, blue, yellow, red, brown, and black. The functions of those wires should be as follows:

light green - reverse lights
dark green - right turn/brake
blue - electric trailer brakes
yellow - left turn/brake
red - 12 volt power
brown - running lights
black - ground

I would also recommend to test the functions of your wires with a circuit tester, part # 40376, to verify the function of the wires on your vehicle. Then, wire your factory wires to the 7-Way using the functions of the wire and not the colors. Vehicle manufacturers have intermittently changed wiring colors over the years.

The Pollak 7 and 4 Way Trailer Connector Socket, part # HM40975, you have referenced is designed to plug into a round factory connector that is usually located above the spare tire on a 2004 Silverado. I am including a link to a install video of the socket being installed on a 2004 Silverado.

expert reply by:
Jeff D

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Follow up Questions

I have the same problem as the gentlemen above but the plug in a new one. Fuses are all good. ?
Etrailer Expert
Reply from Chris R.

If the connector is new and clean, there has to be some crossed wires somewhere along the line on the truck. You will just need to trace the wiring to see where there might be an exposed/damaged section that's touching a nearby wire.

Ben W.
When I hook up to my travel trailer and turn the left signal on, both left and right signal lights flash. I checked the 7 pin connector on the truck side with a test light and it does the same thing. I also checked the yellow and green wires coming into the back of the 7 pin connector and does the same thing. All the fuses are good. Is there a ground wire I am missing somewhere between the connector and the front of the truck?
Etrailer Expert
Reply from Chris R.

You at least know the issue is somewhere on the vehicle (and not the trailer) because of your initial testing. Is this an aftermarket 7-Way or one that came on the vehicle from the factory? If it's decently old, I wonder if there's corrosion inside the pins that are bridging the circuits together - inspect the connector itself and clean out if needed. Let me know what you find.

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