Turn signal issue

[Nick67]

2006 Sierra SLT. 

Left turn signal is always on (& not flashing) on both dash and front/back lights.  Right turn signal works as it should.  Flasher relay has been changed - no change.  The lights themselves illuminate; only right side flashes when asked, left side lights are always on, not flashing.  Any ideas are appreciated!

[Jsdirt]

I'd be checking grounds on either the front or rear bulb (or both), and also check if a broken filament has shorted from the running light side to the turn signal side in the 1157 / 3 or 4157 bulbs. Also check and see if just ONE filament is lighting - if both the turn signal and running light filaments are lit, that's a problem you'll need to track down.

 

Another possibility is wiring damage causing a short to power in the wiring that is not passing through the flasher.

 

I know '07-up are all BCM controlled - can't recall if '06 is or not, but if it is, that'll change things drastically as far as troubleshooting goes.

Edited December 27, 2024 by Jsdirt