Q: Turn signals not working

In my experience, I have come across a number of vehicles, such as with your Chevy Colorado, where multiple light bulbs have gone out at once. Or times where a bulb or two was previously out but only noticeable when the other went out. If you are comfortable removing and replacing your Colorado’s light bulbs, you can check the bulbs to determine if they are in good working order. Replace noticeably bad bulbs, then attempt to use your Chevy’s turn signals and dome lights for normal operation. If the bulbs are good, then the issue may now fall in the body control module or BCM. The BCM is responsible for various functions in your Colorado including use of the turn signals and dome lights. I would highly recommend enlisting the help of certified mechanic so they can properly diagnose why your dome and turn lights are not working.