2014 GMC Rear Blinker Failure..and then others..

DoolOK · December 19, 2024

Hey gang.

First time poster here. Thanks for having this open for people to post...I can't find info on an electrical problem, so I figured, why not..

I own a 2014 GMC Sierra Crew Cab and recently put in LED bulbs with the resistor mod....that worked perfectly..lights all worked, headlights all worked, interior lights worked..

..until it didnt.

What I have now is that my right rear blinker doesnt work, but my right mirror and my right front blinker does. I get the "right rear blinker malfunction" error on my dash.

So I pulled the LEDs and resistors thinking it was causing an issue, and then I replaced the bulbs with new ones. Left blinkers all work perfectly fine.

I still have that happening. No rear blinker. Also when I hit the brakes, the right rear doesn't light up...but again, the left side all works fine.

And then I noticed my interior lights dont work...both manually (via the buttons) or when the door is open. I dont have a switch per say to turn them off and on by my trailer brake controller like some GMC's do...so I know that aint a reason...

I can't find any type of relay that would tie the 2 together, and I've checked all the fuses that I think were tied to it and replaced those on a sheer "why not" moment.

The other night I also noticed my headlight seems to be flickering more and more...great.

I get no check engine lights or stored codes...so that got me nowhere.

Am I looking at a bad BCM here? Or could this all be tied to some singular ground issue somewhere?

I'm clueless at this point.