How do I find a short?

[Rick Lee]

The 5 amp fuse controlling the right front turn signal in my '87 Carrera blows frequently. I changed the headlight/turn signal switch a few weeks ago. So I know that's not the culprit (anymore). Yesterday the fuse blew again. I have replaced it 3 times in 6 wks. Wouldn't a short make it blow right away, every time I replaced it? How do I locate an intermittent short? This is driving me nuts? Thanks.

[pwd72s]

I HOPE (emphasis on HOPE) that the multimeter I bought at Sears today is supposed to help with problems like this...
it has a windows 95 interface, supposedly gives out diagnosis? Haven't played with it enough to tell more. But might be worth consideration? Hook one up until the fuse blows again, see what the read out says? Keep in mind, this just guesswork...

[RoninLB]

full time shorts are easy to find. occasional shorts are more fun. I would start with looking at a wireing diagram to see the exact circuit you are dealing with. I probably would put the circuit in operation and wiggle all wires in that circuit to see if it blows fuse when you do this. Hard to guess without knowing complete circuit. Is fuse sized for circuit? Has any switch or relay in circuit, even if new, been tested and ruled out? I think if you can keep your attention span for one hour you will find it. I would have a volt/ohm meter close by.

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RoninLB

[wellsmokey]

Maybe the turn signal flasher has gone caplooee. Just a thought. Also, are you sure that the fuse is only supposed to be rated at 5 amps. Without checking the owners manual, seems a little small for that application.

[This message has been edited by wellsmokey (edited 09-09-2001).]

[This message has been edited by wellsmokey (edited 09-09-2001).]

[CamB]

RoninLB's comments are pretty good - you know it is shorting somewhere on the wire between the fuse box and the turn signal...

To give you an idea, my electric windows were shorting out peiodically. It became obvious on studying the wire in the door that one of the +12v wires was worn through the insulation.

So I would check the loom to that turn signal, especially where it goes throughtight/sharp places.

Cam

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Cameron Baudinet
1975 911S (in bits)
1969 911T

[Rick Lee]

Thanks guys. As I mentioned, the turn signal switch it a month old, so that's not the problem. I'll get the volt meter out and start tracing that wire for sharp turns. I have the Bentley manual and, unless it's wrong, a 5 amp fuse is what the turn signal needs. The left side has it and it works fine. Must be the wire.

[derkpitt]

Finding intermittent problems are the hardest. First a good wiring diagram. Like the Bentley's manual has. Then a good under standing of the wiring lay out in the car.
Then a cheep multimeter [Radio Shack] with a continuity beeper. Start with the fuse and light bulb removed. With one lead at the fuse the other to ground. Shake down the wiring. If it beeps their a short. Move down the harness till you locate the short. This should get you started.

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Derk Pitt
88 Carrera Coupe