GMC Repair: 1988 Chevy Silverado Taillights, chevy silverado, fuse holder

Question
I have a 1988 Chevy Silverado that keeps blowing the 20A fuse for the taillights/gauge lights. The headlights, brake, turn, etc. still work but the parking lamps and gauge lamps do not. The fuse will only blow when the engine is running. Everything works fine when engine is off. I recently put on a new bed and have checked all grounds and the wiring from the rear to the firewall.

Answer
All I can tell you is that you have a short to ground in that circuit somewhere. I would get an ohm meter and check the wires for resistance to ground.

Also you may want to get a 10amp circuit breaker and put it in the fuse holder in place of the fuse. Start the truck and the circuit breaker should start to cycle on and off. Then start unpluging connectors in the circuit from the rear to the front, and when it stops triping the breaker then the problem is from that point back. I have also been know to cut wires if necessary and repair them after I found the short.