I have a 1987 gmc S15
and can’t figure out something
so the radio gauge lights cabin light horn and at one time the turn signals Went out in it and I was wondering if there is a common wire or ground or relay that they share? Please help me out guys
They're on different circuits powered by different fuses.
Using the link which @mmj provided for you I highlighted the stuff you're having a problem with.
Red for Power and a Dotted Red line where I added to the diagram because it shows the Horn fuse but not the Horn Relay so I stuck the horn relay in there.
And what sticks out by the diagram (even though it does a poor job pointing it out) is that all of these individual circuits have the GM Convenience Center involved in their circuits.
I'll use the same colors to highlight the Convenience Center components as I used in the wiring diagram.
Yours is either in the same location or pretty close. They were typically on the drivers side under the dash somewhere and the long white Audio Alarm Module makes them easy to spot.
Anyway, just something to consider while you're working through this.
Your first step with any electrical problem should be to check fuses + relays
This came up in a quick web search ...
