Left turn signal comes on when i hit brakes

Hello,

This sounds like a problem with the BCM I would have the unit scanned to see what come up.

Here is the location and wiring diagrams for the BCM and the turn signals so you can check the grounds:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-use-a-voltmeter

and

https://www.2carpros.com/articles/how-to-check-wiring

If it does look like the BCM after testing you will need shop to program it for you.

Please let us know what happens.

Cheers, Ken

Bcm tested ok, have replaced the left tail light harness, the turn signal switch, added another ground to the system, brake pedal switch next

Looking at the blinker wiring diagram it looks like the flasher module could be causing the issue as well. Here is its location (below)

I would check the rear junction block for damage moisture.

"Rear Lamps Junction Block On rear inner side of right frame rail."

Please let us know what happens.

Cheers, Ken