I can probably rewire things but my big concern is figuring out why this happened?

After having my car stored for a few years, I went through the process of restarting it. Change plugs, change oil etc. It did start and run well. However smoke began to pour from the vents and I stopped the car. Upon investigation I found fried wires:all of the grounds to the instruments except the clock and the green / white wire that goes to a light on the gauge to the light switch. This is the cars first electrical problem. I can probably rewire things but my big concern is figuring out why this happened.

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[Kerry at Pelican Parts]

Rodents have been known to get into cars and chew on the wiring. I don't know what you mean by "all of the grounds to the instruments" Where the ground wires leaning on the engine or exhaust? Did they burn up without touching anything? If they did they were carrying too much current. Fuses should have blown to protect the circuit. The ground may have corroded and the drop in voltage increases the amp draw. Try cleaning all your grounds.

- Kerry

[Porboynz]

That's a classic problem, the instrument light feed is not fused. I planned to fit a fuse to mine, bought the inline fuse, read up about it on the forum and put it off. Now having read this post its top on my list.

[DennisS]

I traced the burnt green/white wires to the light switch. Then I removed the light switch and found it was burnt on the windings next to the green/white wire. So I would say the light switch failed at the power to the lights, so all the green/white wires have been effected and the brown ground wires at the instruments. All other wires were okay.

Yes an inline fuse wound have halted this from happening.


So I am gathering the information to replace these wires and the light switch. I also will include a fuse in case there was another problem. I will only use the fuse.
The actually is a lot of information on this site and the internet in general regarding the layout of the instrument wiring and the other car lighting.

[al lkosmal]

Originally Posted by Porboynz

That's a classic problem, the instrument light feed is not fused. I planned to fit a fuse to mine, bought the inline fuse, read up about it on the forum and put it off. Now having read this post its top on my list.

+1.................I've been there and done that with my 77S. The lack of a fused circuit ....all you need is one short from power to ground.........and you let the smoke out. Rep0lacing all the burnt bits and adding a fuse is the way to go.

regards,
Al

[86 911 Targa]

Originally Posted by DennisS

I traced the burnt green/white wires to the light switch. Then I removed the light switch and found it was burnt on the windings next to the green/white wire. So I would say the light switch failed at the power to the lights, so all the green/white wires have been effected and the brown ground wires at the instruments. All other wires were okay.

Yes an inline fuse wound have halted this from happening.


So I am gathering the information to replace these wires and the light switch. I also will include a fuse in case there was another problem. I will only use the fuse.
The actually is a lot of information on this site and the internet in general regarding the layout of the instrument wiring and the other car lighting.

On some occasions, the dash light 12V wires can ground on the sliding controls.

Do add a 3A fuse, and check my previous post on fusing, and headlight switch wire connections.

[HawgRyder]

Our cars are old!!
The wiring has been in that car for decades (in most cases).
Wiring can chafe (rub against bad metal objects) from years of vibration.
So...when looking at your wiring...and you should on a regular basis...be careful when bending or moving the bundles...they may be OK where they are...but if you touch them..you might be putting them in harms' way.
I have seen lots of old wires that were so brittle...the insulation would fall off if moved (good old Lucas wires..prince of Darkness...LOL).
If in doubt...replace as much of it as you can...with new (and sometimes better or bigger wires)....and definately...FUSE EVERYTHING!!
Bob