puzzled 900 miles from home

[siii8873]

Vehicle is a 1971 Exmod 109 converted to a Lucas alternator. I had a smoking dash event on my way to NC from NY. The wire that burned is the lead from the ignition warning light to the source side of switched fuse. After this the alternator stopped charging the battery. I put a voltmeter in inspection sockets and coud see battery losing charge. The voltage did not change when reved engine a little. Ran from NY to NC on batteries
I checked the leads from the ignition warning light>Alternator, IGN loation on terminal block>Coil, IGN location on terminal block> fuse location where wire burned, all good. Replaced the burned out wire.
Fired up the truck and could see a rise in voltage 12.7 to 13.4 when reved engine a little. Appears alternator is working. Turned the key off and engine did not shut off. Opened the ignition warning light circuit and engine shuts off. Key switch works it starts and stops engine if ignition warning light circuit is open. The only thing I can think that is going on is that the coil circuit is being back fed through the ingition warning light circuit. I open this circuit and it will shut off, closed the engine continues to run..

[SafeAirOne]

In other words, you suspect your alternator/internal voltage regulator is bad?

If so, the charge lamp should light up when you turn off the key, indicating electrical flow from the batery, through the alternator and through the charge lamp to the supply side of the "hot in run position" fuse bank and then through the coil primary circuit, oil pressure lamp, etc.

I've had a similar situation. Twice. Once when my alternator failed. and again when the new alternator failed a day after installation. The charge lamp illuminated upon shutdown. My engine turned off though (diesel--no coil) and my wiring didnt fry.

[leafsprung]

fried stator can cause this

[siii8873]

Convined it's the alternator. The charge indicator circuit stays energized with the key off, only when the engine was running first. If the engine is off the charge circuit is enrgized with the key on only. This tells me that the path of the short is from the alternator when it is rotating / producing voltage. I temporarly wired the charge circuit through my heater switch so I can shut the truck off.
Alternator should be here today and then back on the road for NY. Do have two fully charged batteries and charger in case.

[Les Parker]

So, Bob, where did you get the replacement alt?

Let us know how you get on, I still beleive the alt has an internal fault/failure.

[siii8873]

I have removed/installed about 4 of these, but always in plain view ie no wing ect in the way and not under the truck in 90+ temps and humidity. Does the sleeve on the rear lower mount have to be shifted? Having trouble removing starter and do not want to damage bracket. I thought the starter came out whitout moving this sleeve out of the way? The sleeve on my alternator at home is froze in position.

[Les Parker]

Not sure how the starter comes into play here...
The sleeve on the alt. should stay on the alt.
Just undo the adjuster bracket, the 2 pivot bolts and the alt should be able to be lifted out (after undoing the elect. plug!)

[siii8873]

I remembered after looking at the new one. Don't know why I said starter. Back in the Binghamton area, NY. An uneventful day today, didn't need to fix anything. 1750 miles so far, about 250 to go.

[siii8873]

well made it the ~1000miles home without any issues. Total trip 2011miles.

[SafeAirOne]

Maybe I missed it somewhere, but did you end up swapping a new alternator in while you were down there, and did it fix the problem?

[siii8873]

Yes I did install a new alternator in the 90+ temps on the blacktop in NC. Stayed a few extra days with my daughter so it was not bad. It solved all the problems. Hindsight wise there were clues. I am now thinking that this was the source of a couple of intermittant problems I was having. Not sure if the wire from the fuse to the charge indicator light came off and made contact with a ground causing the alternator problem or vice versa. I was behind the inst panel recently and may have loosened this wire. It was disconnected and the insulation totally fried off end to end when I looked behind the panel after the smoke.