Cooked VDO Gauge

[rmb_cobra]

I noticed after I returned from DVSF, my ammeter gauge was acting funny, reading abnormally high. The glass became fogged (like it had gotten wet) and stopped working with the indicator pegged at 60+ amps. I pulled it out of the dash last night and the PLUS B terminal wire looked like it had melted, or a rubber or plastic part near the post had burnt.
I have located new gauge, which is on order. Any ideas why it cooked? The wiring harness I inherited with the car is rife with problems, the least being I have no central fuse panel. Most of the wiring has inline fuses all over the car.
Any idea why it would suddenly cook?
Also, my headlight toggle appears to be cooked, and all four of my running lights bulbs exploded...... Lucas strikes again...

Suggestions? New wiring harness perhaps?

[SFfiredog]

A faulty regulator or shorted alternator could have caused the problem but more likely it is the questionable wiring or a bad ground.
I would replace the voltage regulator (it's probably fried too) and at least have the alternator tested.
Depending on the amp output of your alternator (anything over 65 amps) I would recomend a voltmeter over a ampmeter as well. They are safer and more usefull.
I don't think this is exactly what you want to hear but if the wiring in the car now is a butcher job your better off buying a universal wiring kit from a company like Painless or maybe a harness from one of the other Cobra kit manufacturers.
You are lucky all you have is some burned switches a gauge and some wiring.
Your entire car could have burned to the ground.
Oh yeah, for petes sake, put a ford engine in the car, please
--Mike

[rmb_cobra]

Mike,
I had a sneaky suspicion it wasn't just the gauge. When I saw the cooked gauge, I got real nervous. That little fire extinguisher I have wouldn't have slowed it down much.
I will have the items you mentioned tested, and probably look into a new voltage regulator as well.
The other issues happened suddenly after hitting a huge bump in the road. A loose ground could certainly be the culprit.

A new wiring harness (probably a Painless) is in my future, but I don't want to spend the next 3 driving months working on it. I guess that is better than a frame, motor and some fiberglass mesh....
At least you didn't blame it on the engine make! "Ford's never have wiring issues...".

Thanks. Back to the garage.

[SFfiredog]

The big bump...
Check to make sure the positive cable on the battery isn't touching a gound source, or one of the larger power wires isn't worn though and grounding to some metal source.
The ampmeter is usually wired directly to the alternator output power wire so it usually will cook first.
I have a feeling something could be shorting to ground.
Also, like I mentioned, a loose gound will cause excessive resistance, which is HEAT... ooh stinky, stinky, melty, melty, smokey, smokey which is of course, all bad.
--Mike

[tpiini]

Hey rmb,

Let me second the "dump the ammeter" suggestion. When yo do rewire the car, a volt meter will tell you all you need to know and will not have high-amperage wires threading through your dash. Many years ago I watched as my ammeter shorted and made my 10-gauge wires glow brightly until they finally melted. Fortunately, the car didn't burn to the ground.

Ammeters and glass fuel filters; Two things I live without.

Tom