I blow tail light fuse???? Help??? SOLVED

[fyrengineer]

I just bought a 75 C10.  When I drove it home it got dark and my wife noticed from behind I had no tail lights.  I noticed I had no dash lights either.

Working on cars all my life I thought, Hey no problem, just replace the fuse.  Well I wish it was that easy.  I looked at the wiring diagram and saw the tail light wire coming out of the firewall was brown and the front parking lights wire was brown so I decided to cut both of them on the firewall side and work back from there.

But to NO avail, I replaced fuse (20amp) and as soon as I pulled the headlight switch to the parking light position, crack goes the fuse.  The 5 amp fuse that says dash lights is NOT blown and I still have no dash lights.

I have been reading wiring diagrams, scratching my head etc.  I even disconnected the dome light wiring behind the seat.  The fuse says tail light/courtesy light.

I can't figure out what is causing the short that it immediately burns the fuse.  Does the headlight switch go bad?  May that be the problems??? I don't like buying parts to troubleshoot.  I dont mind buying a new headlight switch but don't want to waste my money and that not be the problem.

So long story short, why dont I have dash lights, (they can't ALL be burnt out at once?) and why am I burning through the tail light fuse??

Thanks for any help on the issue.
Bart

[fyrengineer]

OK my chevy truck friends.......I FIGURED IT OUT!!

I hope this helps anyone with this kind of problem.  So this took about 5 hours of trouble shooting.  This is what I did.

1.  Pulled apart the dash, pulled the after market radio and took the pigtail off the back of the headlight switch.
2.  I got a power source from the battery and placed an inline fuse in it, I contacted each pin in the headlight pigtail and found the "brown" wire was shorting out.
3.  I laid under the dash and found the brown wire and orange wire (positive) was taped together and went up under the dash and became an octopus of wires.
4.  I traced the wires down and found that one of the owners cut the orange wire and powered the radio with it.  (the orange wire was supposed to power the courtesy lamp).

Here is the big screw up on the previous owner which kept shorting out my dash and parking lights......
They took the brown wire and connected it to the "ground" coming out of the aftermarket radio.  When they installed the radio it grounded from the dash, in turn it grounded the brown wire feeding back to the fuse box and burnt the fuse.

The fix.....I removed the brown wire from the radio, and grounded the radio properly!!

Walah......now my dash lights work and all my parking lights work!!!!

Hope that helps you guys, now I have to put my dash all back together. 

Now I have to figure out why my gas gauge only goes halfway even when tank is full!!

Take care,
Bart

[Captkaos]

This happens A LOT!