Desperately Seeking Short

Missouri66 · Post by **Missouri66** » September 16, 2009, 11:52 am

Anybody have any magic tricks to share for finding short circuits?

The 14A fuse on the turn signal/ brake lamp circuit blows when turning ignition on. I've started disconnecting wiring harness connections (tail lamp connector, steering column turn signal switch connector) attempting to isolate the problem -- no luck yet.

Jack

ICEMAN6166 · Post by **ICEMAN6166** » September 16, 2009, 11:56 am

my guess
somewhere along the frame or inside the column tube one of the wires is bare/ broken and rubbing against metal.

Anthony · Post by **Anthony** » September 16, 2009, 3:39 pm

sorry to say, but

Anthony

macgiobuin · Post by **macgiobuin** » September 16, 2009, 4:26 pm

Pain in the arse, those wiring issues....

Post by **Greg D** » September 16, 2009, 6:34 pm

Some other spots to check - anyplace the wiring goes through the frame or a body panel. It's not uncommon with trucks & cars this age for the grommets to dry out and disintegrate leaving the wires to rub on the steel, wear through the insulation and short out.

Michelle · Post by **Michelle** » September 16, 2009, 7:57 pm

It sounds like you are on the right track to finding the problem by isolating it. I have enclosed a couple of wiring diagrams that may help you. Try disconnecting the two plugs that come from the steering column as shown in second picture and see if that helps you. The diagram also shows the plug connectors to both the front and rear lights. Just keep disconnecting plugs until you find the stretch of offending wire.

Paul Merrell · Post by **Paul Merrell** » September 16, 2009, 8:14 pm

Bad flasher unplug it

cdherman · Post by **cdherman** » September 16, 2009, 9:39 pm

Paul Merrell wrote:Bad flasher unplug it

,

Short and sweet answer there. Might be right. A rubbing wire on the frame would take a few minutes to blow (takes a while to heat up that fuse).

A hard short, one that was just plain connected to ground might do the damage in shorter time.

Obviously, its a short somewhere. A wiring diagram is a MUST and then you have to start following wires around till you find the culprit.

fmartin_gila · Post by **fmartin_gila** » September 17, 2009, 8:32 am

Jury-rig a light bulb or a buzzer across the fuze terminals. It will activate as long as there is a short, and will limit current flow so you will not do any more harm to the wires than has already been done. when you disconnect the circuit with the short, the light will go out or the buzzer will stop. I prefer a buzzer cause you can go all over the vehicle jiggling wires or disconnecting and connecting and still hear it. I have used this method of short finding for years with very good results. I think the buzzer I use came from a junkyard back in the 70s ignition warning buzzer.

Fred