Troubleshooting Chevy and GMC 12V Wiring on 7-Way Connection for Towing

Updated 01/30/2018 | Published 01/29/2018

Question:

Troubleshooting a trailer hook up wherein the battery for the brakes is not being charged by the tow vehicles. I have measured the voltage on the tow vehicle connectors on both a 2009 Chevy Suburban and 2015 Chevy Tahoe. Neither had +12 on the Battery terminal of the 7-pin connector Pin 4. All other pins had their normal voltage 14.2 volts with the vehicles running + ground on Pin 1. Does Chevy supply these with the Battery lead either not connected or a fuse not in place? Seems strange two GMC vehicles would show the same symptom. Thanks.

asked by: John P

Expert Reply:

Under the hood of many Chevrolet and GMC vehicles there is a connection required for activating the 12V auxiliary power feed on the 7-way. The ring terminal for the 12-volt power lead for the 7-way trailer connector is located to the left of the power distribution box. It is taped to a wire harness under the power brake booster. Cut the tape to release it from the harness. Then run the wire to the front of the power distribution box and hook the ring on the right post. You can refer to the linked article that covers this process.

expert reply by: Jason S