left rear turn signal

[Whatever64]

5 hours ago, Donstar said:

When you swapped bulbs, did you simply try the bulbs from the right on the left side or did you also test the left bulbs on the right side?  Work with the simple stuff first before you start taking things apart.  Next step I would do is as CadillacLuke24 suggested.  Buy some spray for electrical connections and give a good shot to the bulb connector. My truck behaved in a very similar manner shortly after purchase and the culprit was a bulb.  Every spring, I employ the use of my 53 year old utility trailer to do those dirty projects around the property.  A shot of WD40 in the plug, and some air in the tires puts this old girl to work!

a complete swap. the left side was still dead

[Whatever64]

On 3/4/2019 at 7:40 AM, CadillacLuke24 said:

Damn...do you have integrated turn signals in the mirrors?

Yes and they work

[Whatever64]

A final fix... other than a can of gas and a flare

Found a dealer ( West Herr GMC in East Aurora) that could answer my question Is there a fuse for the rear brake and turn signal. There is not. The wires run directly to the BCM. Which was not the problem. After 4 days they found corroded wires under the dash inside the car. Fixed those and it is happy now.  The plugs and harnesses outside were fine. They used common sense troubleshooting and followed the signal....

Hope this helps anyone in the future.