Troubleshooting No Running Lights On A Flat Towed 2011 GMC Acadia

Question:

Hello, My name is Marv, Heres my history. I have a 2011 GMC Acadia AWD that I am modifying to be towed behind my RV. Ive purchased and installed the base plate. The video for the installation was very helpful. Also purchased was the wiring for signal and tail light connection to the RV. This included diodes and I had a problem with this. I could get the signal and brake lights to work. But, the tail lights would not work at all. I thought it was because the tail lights are also on in the hatch. So I ordered HM56107 that plugs into the existing plug and light. I figured this would cure the problem. It did not. Only the brake and signal work. Any recommendations?????

asked by: Marvin C

Expert Reply:

Hello Marv! I am happy to try to help you troubleshoot the wiring issues you are having on your 2011 GMC Acadia. This is an interesting issue you have described, and there are a few things you will want to check.

First, we want to confirm that we do in fact have a solid running light signal coming from your RV. The running light circuit should be at the "11 o'clock" pin on the RV 7 way. We suggest going in with a wire tester like part # PTW2993 and verifying that there is power to the running light circuit on your 7 way plug. This will help narrow down the source of the issue.

If we are getting good signal on the running light circuit, we would next look at the diode kit you installed. A possible explanation is that the diode kit is wired incorrectly. And if the diode kit was left in place with the Hopkins # HM56107 installed, this would explain why neither wiring kit is working correctly. We suggest going in and double checking all of your connections. Also use a wire tester to double check wire function. The running light wire should be run to the top pin of the 6 pin plug.

The universal diode kits that came with your Blue Ox Accessory Kit # BX88308 are known to work fine on a 2011 GMC Acadia, so it seems something must be wrong with the diode wiring. A lot of times in these cases we do recommend taking the vehicle to a certified technician.

expert reply by: Jesse M