Mirror turn signals not working

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Sounds like your truck is being a little picky about its new mirror. Since the task light works but the turn signal doesn’t, the wiring is probably fine, but the truck might not be recognizing the new mirror properly. Some replacement mirrors require reprogramming through a GM scan tool to enable all functions. Double-check the connector pins to make sure none are bent or loose. Otherwise, a dealer or a shop with GM software might need to reprogram the truck to accept the new mirror. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.