Yowzer Posted July 5, 2010 Share Posted July 5, 2010 My brothers car ('79 Chrysler Avenger) is shorting out somewhere, problem is I am lacking a wiring diagram and the fuses are unlabelled. Anyway, what happened, the car was running fine but as soon as I turned on the headlights everything went dead. One of the fuses, an 8A, has a massive current trying to flow through it even with everything turned off. If anyone knows what Fuse 4 is, that would be somewhat helpful as I'd have more of a starting point. Seems weird that it would be cutting power to the whole car though, so I suspect more of an issue elsewhere. Any ideas or tips to try would be helpful Cheers Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 5, 2010 Author Share Posted July 5, 2010 Ok, so the fuse is for the interior lighting.. Therefore I see no reason why this would be effecting the power to the rest of the car... Ideas? Quote Link to comment Share on other sites More sharing options...
UTERUS Posted July 5, 2010 Share Posted July 5, 2010 In the past when i've had to do this and nothing was labelled, i unplugged everything i could and went around with a multimeter measuring resistance to earth. This should atleast narrow it down to which part of the loom the short will be in. Obvious places to start looking are where it would be rubbing on parts, melted plugs and/or switches. If you are feeling game you could replicate the short again and quickly sniff around to see if you can smell where the burning is coming from, but christ be carefull with that. Edit: Same deal with the multimeter, just remember to keep in mind interior lights are usually negative switched Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 5, 2010 Author Share Posted July 5, 2010 Seems it was somehow the interior light.. Don't know how turning on the headlights triggered it, or how it managed to kill the whole car, but after taking the interior light out and putting it back in, everything now works dandy The light itself now works too, which it never did previously. Meh, Lucas electrics... Quote Link to comment Share on other sites More sharing options...
isnowi Posted July 5, 2010 Share Posted July 5, 2010 Seems it was somehow the interior light..Don't know how turning on the headlights triggered it, or how it managed to kill the whole car, but after taking the interior light out and putting it back in, everything now works dandy The light itself now works too, which it never did previously. Meh, Lucas electrics... Just don't let the smoke out, i think that lucas smoke is now out of production and very hard to get hold of... On a lighter note we use to have a sparky who once used a 4 inch nail to fault find on a 110vdc circuit..... replaced the fuse with the nail, turned the lights off, put power on the circuit, and looked for the glowing wiring, Quote Link to comment Share on other sites More sharing options...
David Posted July 5, 2010 Share Posted July 5, 2010 If the Chrysler Avenger wiring is anything like the Chrysler Hunter wiring I have the same problem. The 8A fuse than runs the interia light, glovebox light, boot light and cigar lighter randomly blows. I can have them all running over and over a again and no problems. Then about a month down the track it will just blow? I just go open the glove box or the door one night to find out the aux-lights no longer go. Nasty foult!!! Quote Link to comment Share on other sites More sharing options...
David Posted July 5, 2010 Share Posted July 5, 2010 Instead of blowing a hand fill of fuse links, ive just used a household circuit breaker, tempory wired in place of the glass fuse when trying to find a foult. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 5, 2010 Author Share Posted July 5, 2010 I think the design of the interior light allows the power wire to touch the body. Was the only conclusion I could come to. Still don't know how flicking on the headlights caused the whole car to lose power though Quote Link to comment Share on other sites More sharing options...
johnnyfive Posted July 6, 2010 Share Posted July 6, 2010 Does the engine power run off that lighting fuse too? Such a slight short that only enough current flowed to blow the fuse when the headlights are turned on? An interesting way I've heard (but never tried) to track shorts in cars is to temporarily wire a bulb in place of the fuse that blows, the work your way through the vehicle unplugging and moving sections of wiring, when the bulb goes out, you've found the area of the short. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 6, 2010 Author Share Posted July 6, 2010 Hmmm... Never thought of that. Will try that next time. Nah interior lighting is separate from headlight, separate from engine etc. It seems to be fixed now, but I don't really consider it fixed as I still don't know what actually happened Quote Link to comment Share on other sites More sharing options...
VAGRANT Posted July 28, 2010 Share Posted July 28, 2010 connect a headlight bulb to 2 wires so that if you put power on one wire and earth on the other the light glows brightly. You've just made a short finder!!!! now plug the 2 wires of your short finder into the 2 terminals where the fuse normally goes (1 wire to each terminal) the light will glow bright when you have a short to ground. when you get rid of (or disturb) the short, the light will glow dim! (keep the bulb away from material..... hang it from your rear vision mirror for example.!!) Quote Link to comment Share on other sites More sharing options...
MrMcdoll Posted July 28, 2010 Share Posted July 28, 2010 An interesting way I've heard (but never tried) to track shorts in cars is to temporarily wire a bulb in place of the fuse that blows, the work your way through the vehicle unplugging and moving sections of wiring, when the bulb goes out, you've found the area of the short. HARDCORE big fuck off headlight (as big as possible, which will be fine for anything except the starters current draw) and as said, start at power source and work your way back disconnecting shit untill light turns off never let me down and is perfect for unlabeled circuits Quote Link to comment Share on other sites More sharing options...
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