Trailer Brakes Activate When Lights on 2002 Chevrolet Tahoe are Turned on

Updated 04/25/2018 | Published 04/24/2018

Question:

Purchased a trailer with electronic brakes. The trailer breaks work when hooked up to the original owners Dodge truck. When I plugged into my 7 way the brakes are engaged while the lights are on. I have the factory tow package and also the factory wire harness needed to install an aftermarket controller. My questions How to determine if i have a factory break controller? I presume I dont since I dont see a place to adjust the break power on my dash. I went a purchased one from a local auto parts store and also the corresponding harness which plugs directly into my Tahoe. I stepped through the instructions however, I had the same problem. Controller would detect trailer is attached and once I turned the lights on the brakes were engaged. I was able to use the sync control adjustment on the side of the controller to manually apply the breaks the sync control not the manual control even with the lights turned on. I guess it could have just been a bad controller even thought it was brand new? I have returned the controller and harness since they did not work and now looking for help. Thoughts on what to try next?

asked by: Rick

Expert Reply:

From what you described it sounds like you have some wires crossing paths somewhere on your 2002 Chevrolet Tahoe. With everything wired correctly the only time you should be seeing the brakes on your trailer activated is when you either press your brake pedal (depending on the brake controller) or using the manual override lever (every controller).

What I recommend doing is checking the 7-Way on your Tahoe to make sure everything is functioning properly. Using a circuit tester like part # PTW2993 use the attached photo to ensure that the pins on your 7-Way are activating at the proper times. The pin in the 1 o'clock position will have constant power and the pin in the 5 o'clock position should only receive power when the manual override is used for a brake controller. If you turn your lights on and the pin in the 5 o'clock position is getting power, then you need to check your 7-Way connector for any damage and then move on to your wiring for any damage.

It is very possible that the problem could be on your trailer side. Check the 7-Way connector on it and then all of your grounds and wiring to make sure that they are clean and intact. Since the trailer was working fine with the previous owner the problem is most likely on your Tahoe.

For a brake controller I recommend the Tekonsha Prodigy P2 # 90885 and then using the plug-in adapter # 3025-P to connect it to your Tahoe. The plug that the adapter connects to should be under the driver side dash. This is one of our most reliable controllers and it has received tremendous reviews from our customers.

Try following the troubleshooting steps that I laid out for you and let me know if you still have issues.

expert reply by: Jon G