Q: Lights going on and off in truck

This problem arises with older trucks. The harness, unless it is damaged, is not usually the problem. The problem usually is in the pins coming loose or making bad contact in the fuse box. When this happens, you start loosing your lights intermittently and possibly other functions as well. It is difficult in your situation because you have an older vehicle, and direct replacement parts may not be readily available. A mechanic can diagnose the problem with your lights and will be able to better determine if it is the pins or if they can simply be tightened and pushed back into place. A technician will also help decide whether or not replacements are necessary.