2012 Tahoe LTZ 2wd Left Rear Turn Signal malfunctioning
 

I am hoping someone can point me in the right direction here. My 2012 Chevy Tahoe LTZ left rear blinker/tail light is not working properly. I noticed that the problem only really occurred at night and a neighbor told me that my left rear tail lights were out (the bottom three of the four). When I checked it the next morning they cam on no problem and the blinker worked fine as well. Later that night I checked my tail lights again, and the left rear tail light wouldn't work. When I turned the left blinkers on, the entire left tail light blinks one after the other like directional blinking Christmas lights. I manually turned the headlights from Auto to off that night and the left rear tail light worked fine again.


I have removed the tail light assembly and replaced all of the bulbs. I disconnected the connector for the wiring harness under the rear bumper and inspected it as well. There was nothing out of the ordinary and I cant seem to find a smoking gun. I find it strange that the problem only occurs when the headlights are either manually turned on, or if the headlights are in Auto, only when it is dark. Any direction would be much appreciated.

I'd check the grounding of the tail-light assembly. If you have a multi-meter measure the resistance of the ground wire (may be the black wire) to a clean metal spot on the frame. Start at the wire harness connector, compare left vs. right for proper readings. I've found that a bad ground can cause very weird symptoms that defy logic.

I would go after the head lamp switch... as it seems to be the crux of when the issue happens...