Burnt wires now Rough Idle

[Mrame]

Took the 82 911SC out for the first time this year, It ran fine for about 100 miles until Friday. I began getting this faint burnt wire smell from the clock area. Sunday I began to investigate and found the wire from the light inside the trunk going back to the cigarette lighter and the clock were burnt. (all the way back to the fuse panel). I disconnected the wire from the fuse panel. and that stopped the overheating wires. Now the car idles rough and there is no power. I can live without the courtesy lights and cigarette lighter. So my question is what other electronic components gets its source fron this circuit that I can safely bypass.

[boyt911sc]

Originally Posted by Mrame

Took the 82 911SC out for the first time this year, It ran fine for about 100 miles until Friday. I began getting this faint burnt wire smell from the clock area. Sunday I began to investigate and found the wire from the light inside the trunk going back to the cigarette lighter and the clock were burnt. (all the way back to the fuse panel). I disconnected the wire from the fuse panel. and that stopped the overheating wires. Now the car idles rough and there is no power. I can live without the courtesy lights and cigarette lighter. So my question is what other electronic components gets its source fron this circuit that I can safely bypass.

Mrame,

Disconnecting the power line from fuse #18 would disable the following:

interior lights
clock
glove & luggage compartments
cigarette lighter
FV (frequency valve).

Without a working FV, you would experience inconsistent and rough engine speed. Also check your relay at this point. Something is over-loading the circuit, one of the many components is surely causing this problem. How many wires were connected to the fuse? Two? Keep us posted.

Tony

[john walker's workshop]

a disconnected hood light wire will short to ground eventually and smoke the dash wire harness. if you disconnect it, tape the end. yes, the dome light fuse also supplies 12V to the oxy relay, computer and FV.

[Mrame]

John the dome light is disconnected, but the ends are taped. I guess it shorted off some how. Tony there were 2 wires on that fuse, now one. Thanks guys for the quick response and help.

[jluetjen]

My experience is that just pulling the fuse while continuing is a very risky decision. If you've toasted the wires in the dash, you most likely have related issues that you haven't noticed yet.

I strongly suggest that you park the car and methodically go through and remove all of the burnt wires and replace them (or more accurately replace the loom). There's a good chance that they damaged other circuits in the loom. Once you've done that you'll be able to start trouble-shooting for which part of the circuit caused the fire.

Do you have a quick-disconnect for the ground on the battery? I strongly suggest that you get one of these because if you have an electrical fire, hitting it with an extinguisher will NOT put it out. The only thing that will stop it is to separate the ground from the battery.

[boyt911sc]

Originally Posted by Mrame

John the dome light is disconnected, but the ends are taped. I guess it shorted off some how. Tony there were 2 wires on that fuse, now one. Thanks guys for the quick response and help.

Mrame,

The black wire supplies power to the courtesy (interior) lights, glove & luggage compartments, clock, etc. The red wire supplies power to FV relay and ECU. These are two separate circuits. Which of two wires is still connected to fuse #18? Black or red? Keep us posted.

Tony

[Mrame]

John, I am at work right now, I will check tonight when I get home to see which wire is still connected.

thanks guys

[86 911 Targa]

Originally Posted by Mrame

John, I am at work right now, I will check tonight when I get home to see which wire is still connected.

thanks guys

And, after replacing/repairing the harness please do this:






Good luck,

Gerry

[dshepp806]

BIG +1 on Gerry's post! I certainly have done that already!!!!!!!!!

A MUST DO!!!!!!!!!!

BEST!

Doyle

[Mrame]

Wow, its difficult to understand why Porsche did not fuse that wire. Now that the circuit is destroyed. I have to rebuild it and make sure its fused. Thanks Gerry. I attached a picture of the fuse panel, the black wire seems ok. What do I need to check/Do to get the system running smooth again? I think I labeled where it connected wrong, It connects to the red and white.
Thanks, Mike.