Why are my 2015 GMC Sierra headlights not working?

If Your headlights in the 2015 GMC Sierra are not working it could be several different reasons. Some of the common issues are a bad relay, blown bulb or fuse, or a damaged wire / corroded ground. You will have to do some inspection to find out what the issue may be and diagnose the problem. The first thing You want to find out is if the fuse and the relay are good. You'll be able to locate them in the fuse panel within the engine bay. Then You should switch on to the headlights and use the ohm meter to see if You're getting power to the headlights. IF You are not getting power it will be a bad bulb. The cost for a replacement headlight bulb will range from $10 - $50 depending on the brand and quality.