My trucks stock gauges are fluctuating a lot when I'm driving down the road. The dash lights, radio, headlights don't get brighter and my speedometer doesn't move either. My fuel, temp, and oil gauge jump up and down though. What could be doing this?

 

First advice is usually to check grounds. Battery to cable, cable to block, cable to body, gauge cluster to body, etc.

Strange things can happen when ground connections get bad.

JP.