Greeting from Middle Tennessee.

I had a recent incident with my 1950 F1 panel truck. I had the truck out in a driving rain storm (gotta love those vacuum wipers and Rain-X). Anyway, got it in the garage, and didn't realize the heater fan (which I turned on to defrost the windows in the rain), is wired to the ignition switch so it is always on. I forgot to turn the fan off which ran down the battery over night.

Next day I tried to start the truck, and NADA. Second time I turned the ignition switch on, smoke came billowing out from under the dash. On investigation, something in the instrument cluster wring under the dash had shorted the 6 volts to ground, and three wires were burned up. That old cotton cloth insulation sure does smoke a lot.

I rang out the wiring and found the ones burned up, and replaced them. One of the burned out wires came from the Circuit Breaker to the Temp Gauge bus, which powers all of the gauges in the instrument cluster. That wire fried as well as the yellow 6 volt wire that comes from the BATT terminal on the voltage regulator under the hood. The scary thing is the CIRCUIT BREAKER NEVER OPENED. Had it been a fuse I thinkit would have limited or completely eliminated the wire damage.

I told my wife the hardest thing about fixing it was getting the smoke back into the wires. : - )

I think the PO replaced the wiring harness, and it looks pretty good, except where he might have tapped into the harness to add some accessories. There, the wiring is very suspect IMHO. I think I am going to get some "period correct" wire with cloth covering over the XLPE insulation, to maintain the original Ford look and color code. If I can figure out how to put a fuse panel into every circuit I will do that too.

Two things learned from this:

1. I will always have a fire extinguisher in the cab when I drive the truck.

2. I am glad the wiring is all original Ford color code and I have a BIG wiring diagram in color that I bought. It made trouble shooting and repairs a lot easier.

Joe W

 

Good idea. Not one of those cute little jobs either, full size extinguisher or don't bother.

Another addition recently added to my rolling pile is a battery quick disconnect. They are only a couple bucks. Real handy at times.

 

The power to the gauges should be coming from the ignition switch, not the circuit breaker. I'd check all your wiring closely!

 

Ross,

Yes, I think I wasn't clear. The black / green wire from the ignition switch to the gauge cluster bus is one of them that burned. The wire that provides the 6V that powers the gauge cluster through the ignition switch on the other side is yellow. That one comes from the voltage regulator BATT terminal and then feeds from the circuit breaker to the gauge cluster. Those wires all burned. The breaker should have opened unless it's just a worthless P.O.S.

Obviously the short happened in the gauge cluster based on where the wires burned.

I no longer trust the "circuit protective devices" in the system. I spend 40 years in the electrical business, and I know a little about circuit protection. It could have been a lot worse. Fortunately I was in the truck when it happened and I turned the key off immediately.

Joe W