Trailer Brakes Do Not Work on a 2003 GMC 2500 With a Factory Tow Package

Updated 06/04/2013 | Published 05/29/2013

Products Featured in This Question

Twist-in, 7-Pole, RV-Style Trailer Connector for Chevy and GMC Vehicles - Vehicle End

(621)

$21.09

Tekonsha Plug-In Wiring Adapter for Electric Brake Controllers - GM

(1197)

$21.73

Question:

I have a 2003 GMC 2500 with a dura Max engine. Factory tow package .my problem isthat my trailer brakes do not work. The problem seems to be with rt he pick up. Any ideas

asked by: Howard B

Expert Reply:

To start off you need to check under the hood to make sure the wiring connection mentioned in the GM brake controller FAQ article attached are made. In the 2002 - 2003 model years, GMC changed the way you hook up the brake controller under the dash. There are two possible wiring adapters that will fit the connector under the dash. The 3015-P and the 3025-P. The only difference between the two is the way the RED wire is pinned out. The red wire carries the signal from the stop light switch, telling the controller when the trucks brake pedal is being pressed. If you have the wrong connector, the controller WILL operate with the manual control, but NOT with the brake pedal.

I have attached a short installation video for a 2005 GMC with the # 3015-P.

If all this checks out okay, then check out the FAQ article I have attached on troubleshooting brake controllers.

You might also have a blown fuse. In your fuse panel, inside the compartment should be a legend listing the fuse locations. Check the fuse for the brake circuit and replace it if you determine it was blown.

The next step would be to check the brake pin on your tow vehicle. Use a circuit tester such as Quickee # 3808 and check the pin located at 5:00 for voltage. If no voltage registers, then check the pin for corrosion or damage. A bent pin can negate the voltage thru-put. I have attached a FAQ covering trailer wiring.

If you find that your problem does lie in your factory connector, the Pollak Trailer Connector, # PK11916 that you referenced is the correct replacement part.