headlights / speedometer

Does anybody know why my speedometer would quit working when i turn my headlights on? My drl lights quit working right before this problem happened. Any ideas. thanks.

depending on the year of your truck it could be the same problem I have run into on a few different GM applications, I had a faulty ground

I simply found a ground wire in the dash and spliced in a new ground wire and attached it to the steering column mount.

Problem solved