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Fuse blowing

Posted: Mon Aug 06, 2007 8:47 pm
by billyg
I've searched the forum and was unable to find anything addressing my problem so here goes; the fuse for the running (front sides and rear back) lights, which is fuse # 13 in the box blows as soon as I put one in. This is also the circuit for the dome light but it still fries it with the dome bulb out and the cannon plug connecting the entire back end (underneath the bed in back right about 2 feet from the bumper) disconnected. I tried to trace it using the manual (factory) but it's a real eye chart. So it's a dead ground somewhere in the system and I was wondering if anybody else had run across this. Headlamps/Brake lights and signals still work fine.

I did find the plug under the passenger seat which removes more of the circuit toward the back of the truck, uncoupled it, and it still blew so it's somewhere towards the front, including under the dash. Any pointers appreciated.

BTW, PHILLIP, hope your feeling better!

Posted: Tue Aug 07, 2007 7:01 am
by asavage
See the 1982 FSM lighting wiring diagram (not schematic).

Disconnect connector 102M/1C. Current draw OK? Then the short is on the rear circuit.

If current draw is still excessive, cut wire Red/Yellow as it comes out of connector 76M as it exits the MF switch. Current draw OK? Short is in front circuit.

Still excessive current? Bad MF switch.

Without doing this diagnosis tree, my best guess? Front turn sig/marker lamp sockets and their harnesses. They are the most vulnerable. I have seen (once) a shorted dual-filament lamp, so you may as well take apart both front turn sig sockets, remove lamps, clean out sockets. The wires can break at the solder pads in the bottom of the socket where the bulb contacts. Wire comes loose from the fibreboard disk, shorts to the metal socket. But that is only a guess.

Short at the interior light

Posted: Sat May 11, 2013 11:44 am
by billyg
fixed and no problems since, just for the record.

Posted: Sat May 11, 2013 3:30 pm
by asavage
OK, but what did you fix?

blown fuse

Posted: Sat May 11, 2013 8:31 pm
by billyg
Sorry, the interior light was on one of the legs of the circuit and when i pulled the fixture to check it, there was a wire that had cracked and was grounding out on the underside of the roof.

Posted: Sat May 11, 2013 9:02 pm
by asavage
It's good to know what the problem was, as people are always coming here via a Google search and looking for answers. Thanks, Bill.