Tekonsha P2 Trailer Brake Controller Does Not Recognize Trailer Connected to a 2004 GMC Sierra  

Question:

Expert Reply:

If you are not getting any display with the trailer connected it could be that the Prodigy P2, # 90885, has lost power or has a bad ground connection. It is also possible that you will need to make some connections under the hood to power the brake controller and make the 7-Way trailer connector fully functional.

On some models of the 2004 GMC Sierra, even with a tow package, there are still some connections that will need to be made. This requires access to the accessory fuse block. I have included a link to our FAQ article that explains how to make the connections and I will also outline them here.

Under the hood, you will need to remove the bracket in the corner closest to the driver. You will then remove the upper and lower covers of the accessory fuse block.

Next to the fuse block on the cab side you will find a red and blue wire. The blue wire has a plug on the end and the red wire has a ring terminal. Connect the red wire to the nearest positive post located on the passenger side of the accessory fuse block. There is a spot right next to this post for a fuse. Using the brake controller instructions, determine if you need a 20 or 30 amp fuse and place it in this location to power the brake controller.

The blue wire comes in from the port in the cab of the vehicle where you connected the brake controller. If it is not ran back to the 7-Way, you will need to do it manually. The brake controller will show NC for not connected if the blue wire is not connected to the 7-Way. If a 12 volt power wire is also needed, you will need to connect a wire to the front positive post on the passenger side of the fuse block and route the wire back to the 7-Way. You will need a 40 amp fuse in the location closest to the post.

If the post is in use, you can connect the wire to the positive battery terminal via a 40 amp circuit breaker, # PK54540. If wire is needed use # 10-2-1 (2 wires) or # 10-1-1 (1 wire). Wire is sold in increments of 1 foot and I recommend 25 feet. You would enter 25 in the quantity box for 25 feet of wire. When routing wires under the vehicle, be sure to avoid areas that may pinch or burn the wire.

If the brake controller is giving other error messages, let me know what they are and I will help troubleshoot further.

expert reply by: Michael H

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