A few weeks ago, I pulled a U-Haul trailer down to GA and back. Had no issues. Didn't think much of it after returning the trailer. Last week, I noticed my turn signals seemed to be flashing faster, which usually means a blown bulb. I checked it and both rear bulbs were blown, as well as the fuse. Replaced all three. Took about three minutes for the fuse to blow again.

I'm assuming this probably has something to do with the factory trailer wiring setup. As it stands right now, imhave running lights on the back, but the right side stays on bright all the time (both filaments), but no blinkers or brake lights. Fuse blows the minute you step on the brake pedal. Any suggestions on where to start troubleshooting. Thanks.

 

The wire harness to the trailer hitch plug and rear lights have been known to rub the chassis under the bumper and short. Open the rear door and see if the harness is touching anything where it feed toward the license plate and trailer hitch plug. Inspect the wiring for missing insulation.

Another common problem, people do not clean out the trailer plug receptacle from all kinds of built up crud which can get wet and short across the plug contacts. Open the lid and inspect, spray with electric contact cleaner if needed.

Easy stuff first.

 

Thanks Doc! I'll give those a try.

 

UPDATE: found two wires cut and grounding, so that's what was blowing my fuses. Got it all put back together and the right brake light still stays on. Everything else works as normal. The guy at the shop says his scanner says it is a bad BCM. Anything else we should check before I spring for a new BCM? There are no other apparent symptoms. Just the right brake light staying on.

 

https://www.hummerforums.com/forum/h...erratic-27553/

Found this old thread that pretty much has all of my same issues. After lots of troubleshooting, they came to the same conclusion. Bad BCM. So I guess I'll bite the bullet and go buy a BCM. Thanks for all the help, guys.