1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Need help troubleshooting a short

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Old Jan 2, 2008 | 10:17 PM
  #1  
lfd75's Avatar
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From: Vancouver, BC Canada
Need help troubleshooting a short

Hi all,

I need help with a short on the circuit controlling the lighter, dome light, hatch light, etc (it an '83 GSL). The fuse is blown and it blows as soon as I replace it. I tried replacing the lighter because it was corroded but the short is still there. Now I've been looking at the wiring diagram and I think since the fuse blows as soon as I put it in the short must be somewhere between the fuse block and the point where the wires split. Is this proper electrical thinking? or could the short be anywhere in the wiring. If so what would be the best way to actually find it? do I have to remove the dash, if so would it be possible (i.e. easier) to just remove the wiring and replace it with a new line?. I'm not too familiar with electrical work (though I did take 1st year physics so I do know a bit of the theory).

Luis
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Old Jan 3, 2008 | 03:43 PM
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More than likely there's a section of the wire that's been exposed and is grounding out somewhere. Look in the wiring diagram for the power wire and go from there. When I got underneath my dash, I noticed a couple wires with the insulation gone.
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Old Jan 4, 2008 | 07:40 AM
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You'll probably have to identify everything that is on that circuit. Looking at the '83 wiring diagram, it looks like these things are on the same circuit:

CPU
Ignition key reminder switch
Ignition switch light
Lights off reminder chime
Interior and spot light (dome light)
Cigarette lighter
Clock
Luggage compartment light

The best thing to do would be to disconnect every one of these things to see if it's the device causing the problem. Then if this causes the short to go away, start reconnecting them one at a time until the short returns, and you've found the culprit. If the short remains, then you have a pinched wire somewhere between the fuse and one of these devices and you'll just have to start tracing...not fun. Start with the easiest ones...probably the dome light, clock, and the cigarette lighter, then the stuff in the steering column (Ignition key reminder switch, Ignition switch light, Lights off reminder chime), then probably the luggage compartment light, and finally the CPU.

Have fun!

Rich
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Old Jan 4, 2008 | 05:04 PM
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just another joe
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From: Pascagoula, MS
one thing to help you along is take a blown fuse and wrap a 2 ft wire around one blade of the fuse and another 2 ft wire on the other blade. insert fuse. put a test light between the wires. meaning connect the ground of the light to one wire and the other wire wrap around the probe of the light. tape to the top of your steering wheel or somewhere in sight. the short to ground will cause the light to light up. when you find your short it will go out. good luck. this is espically helpful since you dont continually blow fuses it see if you found a short. seeings how the dome light comes on when you open the door close doors after each trial
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Old Jan 5, 2008 | 10:24 AM
  #5  
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From: Cedar Rapids, Iowa
Originally Posted by 1983GSP
one thing to help you along is take a blown fuse and wrap a 2 ft wire around one blade of the fuse and another 2 ft wire on the other blade. insert fuse. put a test light between the wires. meaning connect the ground of the light to one wire and the other wire wrap around the probe of the light. tape to the top of your steering wheel or somewhere in sight. the short to ground will cause the light to light up. when you find your short it will go out. good luck. this is espically helpful since you dont continually blow fuses it see if you found a short. seeings how the dome light comes on when you open the door close doors after each trial
Great idea!

Rich
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Old Jan 5, 2008 | 11:56 AM
  #6  
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I had a similar problem and it turned out to be the keylock light in the door. I don't know if all models had them but it was hard for me to find because I had no idea there was one in there. Just a thought.
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Old Jan 5, 2008 | 02:49 PM
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From: Vancouver, BC Canada
Thanks for the replies everyone,

I'll start with unpluging all the components and testing if the short remains. Then I'll move on to tracing wires and keep you posted. One last question about the test light trick (very ingenious btw) Do I wrap the wiring around the blade ends of the fuse? and I'm assuming I would use a normal testlight (not a self powered one) is this correct?
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Old Jan 5, 2008 | 02:58 PM
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Yeah I have been taught and use a method similar to what 1983GSP mentioned. Except you wire a old style (like ours) halagon headlamp to the high beam and put it in series in the circuit where the fuse went. You mess around with the wiring harness for a bit and you will know exactly when it shuts off that you have found the problem area.
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Old Jan 5, 2008 | 07:15 PM
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just another joe
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From: Pascagoula, MS
wrap one wire around one blade. do not i repeat do not wrap both blades with one wire. one wire per blade.
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