Troubleshooting Trailer Brakes that Engage when Trailer is Connected to a 2002 Chevy Silverado

Question:

I HAVE THE TOW PACKAGE FROM FACTORY AND BOUGHT THE BRAKE CONTROLER HAD A GM DEALER INSTALL IT BROUGHT THE TRUCK HOME HOOKED UP AND PLUGGED TRAILER TO ADAPTER BRAKES INSTANTLY LOCKED CLUELESS AFTER HOURS OF TRIAL AND ERROR MOSTLY ERROR. I HAVE THE PRODIGY. THEY WORK FINE ON MY 78 TRUCK WITH A TEKONSHA VOYAGER

asked by: BADDAWG

Expert Reply:

It sounds as if there is constant power being supplied to the brake feed circuit on your vehicle, since the trailer is working correctly with another vehicle. Start out by using a circuit tester, item # PTW2993 if needed, to test the trailer connector at the rear of the vehicle. Looking at the connector with the access door up the terminal at the 5 o-clock position will be the brake feed circuit (see link). Ground the tester and touch the probe to this terminal. If there is power on this terminal at any time other than when the brakes are applied, or the manual lever is activated then the vehicle wiring will need to be checked.

The power wire under the hood from the post that is powered through the 30-amp fuse should be connected to the brake controller power wire (see link). This power wire is terminated in the panel under the dash and should give you constant power on the brake controller Wiring Adapter for 1999-02 Chevrolet, GMC, Cadillac, item # 3025-S, that is connected to the Prodigy, item # 90885 brake controller.

Check the black wire going into the brake controller for constant 12 volt power. If this wire does not have power then check the blue brake output wire for constant 12 volt power. If the black wire does not have power and the blue brake controller output wire does have power this is the source of your problem. You will need to make sure that the brake controller is wired to the adapter properly and that the vehicle is wired properly.

Make sure that the wires coming from the under dash connector have the correct functions on them. The black wire connection should have 12 volt power, the red wire connection should have power when the brake pedal is activated and the white wire connection should be ground. The blue wire connection should have power once the brake controller is connected and the brakes or manual lever are activated.

If everything under the dash is working properly then you will need to check the trailer connector at the back of the vehicle and on the trailer to make sure they are both wired the same. The Wiring FAQ I have linked below has photos of the connectors and wire placement is illustrated for ease of determining which wires should be connected where.