Electrical gremlins are a nightmare to track down. Sometimes it takes the experience of having seen it before to come up with a solution.
Q. I have a 1998 Chevrolet Tahoe that when the lights are turned on everything is fine. The problem happens when the lights are turned off. When the lights are off, sometimes the dash lights, headlights and turn signals flicker-not bright just a click and flicker. This doesn’t happen all the time and it is an old truck so I don’t want to put much into it. I did look at all the major connections and swapped a couple of relays and everything looks okay, any ideas?
A. I remember something like this years ago that has to do with a faulty turn signal switch. I discovered it by carefully moving the turn signal lever with the key off and the emergency flashers on and finding that the radio would come on. This happened because the turn signal switch was worn enough that the brass contacts that made up the switch disintegrated and the brass filings from the switch would cause a back-feed to the radio. I willing to bet that something similar is happening and replacing the turn signal switch will solve the issue.