Troubleshooting Trailer Brake Wiring Issues on a 2002 Chevy Silverado

Updated 06/28/2024 | Published 03/09/2015

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Question:

When park lights are turned on, than the trailer brakes come on brake controller shows its working. 2002 Chev. Silverado was used on other trailers and worked fine. I bought rv. to pull, and when I connected the plug in the trailer brakes never worked or controller. than I went to turn on park lights while moving slowly and brakes came on the trailer. I did some troubleshooting and replaced truck 7 pin plug. still did not work. than found 40 amp fuse blown 0n truck fuse panel. still when I turn on park lights the controller shoes use. and brake pedal does not activate controller. but shows a c for connection. the controller is a prodigy. also left tail light on trailer is always dimmer than right side. Kind of lost what to do next so any ideas what to try next would be much appreciated. thank you.

asked by: Chris

Expert Reply:

Thank you for being very detailed with your question!

The first step I would take is to make sure everything on the truck and trailer is wired properly. Your Prodigy brake controller should have the wiring adapter # 3025-P which is custom for your 2002 Chevy Silverado. I recommend verifying you have the correct adapter because # 3015-P will also fit but it was pinned differently for the 2003-2006 Chevy Silverado's.

The next thing I would check is the wiring for the 7-way connector at the rear bumper. Make sure there are no wires that have been pinched together or cut allowing wires to touch each other. If everything on the truck looks correct, then I recommend testing the truck using a circuit tester like # PTW2993. Having a friend in the truck activating the lights and brake controller functions while you test the pins on the 7-way for proper function. See the diagram I included showing you the pin functions of a vehicle side 7-way connector.

If the truck tests fine, then we know the problem is on the trailer. Check the ground connections ensuring the connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces. See if there is any exposed or frayed wire and fix as necessary.

The lights dimming on the trailer (one side more than the other) could result in having a bad ground or short, and when you depress the brakes causes excessive drain on your battery. It may also be possible that there are too many lights on your trailer which causes excessive load on truck.

I included several helpful articles for you as well. If you are unable to find the problem or a solution, let me know what you come up with and I would be more than happy to help with further troubleshooting.

expert reply by: Chris B

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Alex R.

6/28/2024

Thank you Chris B!!! i didn’t know that the adapter changes from 99-02 & 03-06 ! i had purchased a 03+ adapter so my brakes were engaged all the time time and i had to set my gain to 0. Thanks to you i was able to figure out that my plug is for 03+ so all i had to do is repin the connector to 99-02 (aka move the red wire) and it works perfectly now!!! thanks again !!!!