Troubleshooting No Power To Trailer Brakes When Trailer Connected To New GM Truck
Updated 02/05/2025 | Published 05/25/2021 >
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Question:
Hooked up a 2018, 2019 and 2021 GM truck to trailer and no power to trailer brakes? Blue wire Hooked up 2021 Ford F150 and no problem, Trailer brakes have power! Can you point me in the right direction to fix GM truck? All other lights on trailer work fine, just no power to Brakes
asked by: Robert P
Expert Reply:
When you hooked up to the GM trucks, did you notice if the truck said trailer connected?
The towing computer on the newer GMC trucks is kind of finicky and if it did not recognize the trailer, or the trailer was not setup in the system it will not send power to the trailer brakes.
If you were getting the no trailer connected message you will need to use the 7-Way Trailer Adapter # C57003 which has load resistors and will help the computer detect the trailer.
If the trailer was not setup in the system after being connected, you will need to do that first before the truck will send power to the brakes.
If this does not fix your issue just let me know and we can go into more in-depth trouble shooting steps.

Kelly
2/5/2025
IM not getting any responses from you but I keep getting emails that you sent a response

Product Page this Question was Asked From
Pollak Metal 7-Pole, RV-Style Trailer Socket - Vehicle End
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- 7 Blade
- Plug Only
- Pollak
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Kelly
2/4/2025
My 2021 Chevy 4500 does not have power at the blue wire at the 7 wire connector for the trailer brakes and the dash does not say “trailer connected”. So I have no trailer brakes. Can you help?