Troubleshooting Trailer Turn Signals Malfunctioning with 2007 GMC Acadia with 4-Pole Wiring

Question:

I have an 07 acadia and i bought the pig tail adapter from you guys this may. When i turn the turn signal on, left or right, they both blink like the hazards are on. I disconnected the trailer and the lights blink normal. I went through and bought all new lights and wired on the trailer, new grounds on the vehicle amd trailer and im still having the same issue. Please advise...

asked by: Donovan J

Expert Reply:

The problem you describe, both trailer turn signals activating when either turn signal on the Acadia is engaged, is typically a grounding issue. Since you have already re-worked both the vehicle and trailer main grounds to ensure both are solidly connected to clean bare metal surfaces, then the most likely cause for the problem is either a bad wiring harness on the Acadia or some issue with your adapter.

I could not find purchase history to let me see the specific wiring harness and adapter items you have but you can test your vehicle wiring using a circuit tester like # PTW2992 to see if the signals are correct. You'll want to do this without the trailer connected, as shown in the linked video.

Sometimes corrosion can develop inside trailer connectors (as well as inside wiring adapters like 7-way to 4-pole adapter # PK12716) and that corrosion can cause all sorts of issues too, including odd behavior from the trailer lights. By testing the vehicle wiring on its own you can determine if the lighting signals are correct on the Acadia. If not you may need a new 4-pole wiring harness like # 118384.

expert reply by: Adam R