Dash/taillights circuit keeps blowing fuse Please help !!

[MountainGoat1966]

84 K10.
The fuse for dash lights, courtesy interior lights, (no dome lamp) and taillights keeps blowing, and it's a strong arc when a new fuse is installed.
I have the harness to the rear lights disconnected, the headlight switch disconnected, the dash & gauges are out and disconnected, ignition switch disconnected.
But it still blows the fuse as soon as I try to install a new one.
I'm having a hard time tracking down this gremlin.
Can anybody help me with some advice where to look next?
Everything else on the truck works fine and fuses are good for all the other circuits.

[ray_mcavoy]

Looking at the 1984 wiring diagram, I can see that the output of the "TL CTSY" fuse is an orange wire (circuit #40). It runs directly from the fuse to the headlight switch connector. Then a second branch of that circuit (crimped together on the same terminal) runs from the headlight switch connector to the under-dash courtesy light.

Since you have the headlight switch unplugged, that rules out the switch and any other circuits it feeds (like the dash & tail lights and/or their wiring). So the problem is most likely a short to ground somewhere along the circuit #40 orange wire. Look over the wiring closely to see if the orange wire has been chafed, pinched, or otherwise damaged & shorted to ground.

[MountainGoat1966]

Thanks, I am hobbling out to the truck now to do some looking.

[MountainGoat1966]

THANK YOU !!!
Your advice led to the solution.
WEIRD as it may be, but then again, weird unexplainable things happen here all the time.
The stories I could tell would send shivers down your spine.
My helper started looking at all the orange wires, fixtures of underdash lights, connectors, etc.
Keep in mind the underdash courtesy lights have been working perfectly for years, zero issues.
When he removed a bulb, we found the short circuit, there is a strand of wire from the center connector to the shell.
I installed a new fuse in the fuseblock, and it didn't blow.
Question is, HOW the heck did it get there suddenly and out of the clear blue sky ??

[ray_mcavoy]

Originally Posted by MountainGoat1966

THANK YOU !!!
Your advice led to the solution.

You're welcome! Glad you found the problem!

Originally Posted by MountainGoat1966

When he removed a bulb, we found the short circuit, there is a strand of wire from the center connector to the shell.
I installed a new fuse in the fuseblock, and it didn't blow.
Question is, HOW the heck did it get there suddenly and out of the clear blue sky ??

Might want to check for gremlins