Interior Trailer Lights Not Working When Connected to a 2011 GMC Sierra Denali

Question:

Just purchased a 2016 Triton snowmobile trailer and have a gmc 2011 denali pick-up truck. All lights work except the interior trailer dome lights. Any suggestions. Thanks

asked by: Dan

Expert Reply:

The interior dome lights on your trailer likely run off of either a trailer mounted battery or directly off of the 12 volt circuit from the trailer connector (if it uses a 7-Way connector). If they connect to a battery then check to see if the battery is good, needs a charge, or needs to be replaced. To keep a trailer battery charged and maintained I recommend hooking it up to a CTEK battery charger, # CTEK56353, which will charge and recondition a battery.

If the lights don't run off of a battery but instead run off of the 12 volt circuit then the issue is probably with the tow package wiring on the truck. GM trucks like your 2011 GMC Sierra Denali, even ones with a factory tow package, sometimes do not have the tow package wiring fully connected or the fuse for the 12 volt circuit could be missing.

Under the hood of the truck 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 (the lid will have to be removed). 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 (M8 stud). If you need an M8 nut use # 185917. Activate the 12-volt power lead post by inserting an automotive style 40-amp fuse into the correct slot in the power distribution box.

expert reply by: Michael H