Just about burned my Charger to the ground today.
Taking it into town to get some tools so I can pull bearings out of the Dana 35 rear in my Wrangler (slide hammer has gone missing somehow, need a replacement). Cold, so the windows were up (thank GOD). About ten minutes into the drive, I think "farmers are burnin' plastic with their trash again..." Then I make a right turn, the sun crosses the dash, and I see wisps of smoke coming out of the defrost vents. Quick glance shows the ammeter PEGGED...at idle.
(*^$*&^#($*&(*@#!!!!!!!!!
Pull off, pop the hood, hit the battery disconnect, grab the extinguisher out of the back seat, and start poking around.
EVERYTHING in the dash is OEM, original, untouched, 1970 parts. I made TWO changes when I got the car - rewired the headlight switch so the dash lights are simply "on" (bypassed the dimmer), and replaced the gauge light bulbs with LEDs. This was all nearly 4 years ago, so I knew it wasn't that. If those were wrong, it would have manifested long before now.
I was having a no-charge situation last summer (Carlisle, actually), and through troubleshooting, I found the (again, OEM 1970) underhood harness was trashed, so I replaced the engine harness, and the a/c harness (since I had it). Aha! It charges again! Since then, I've just been driving it...but in nice weather, with the windows down. All gauges have been reading fine, with the exception of the fuel gauge which I have traced to a bad sender (it's pegged over full when the sender is plugged in; unplug it at the tank and it drops to zero). I just hadn't had a chance to install the new sending unit yet, always too much fuel in the tank.
So, back to today. I pull the screws out of the cluster to try and get it out a little bit. Pull the fascia off the radio. Can't drop the column because I didn't have a deep socket (gonna fix that right quick, and put together a traveling toolbox for the trunk!). But got about an inch to see behind the ammeter, and could DEFINITELY smell hot electronics. I've fried enough wires in my day to be able to tell nothing was actively burning, so I (being about ten minutes from home) hooked the battery back up and started the car to drive home. Normally, the ammeter wanders around the plus side of the gauge for a couple minutes after starting, to replace the crank voltage, then settles in to the center of the gauge. Not this time. It was 3/4 up at idle; step on the gas to get the car to move, it pegged.
Now, when I had the no-charge issue this summer, one of the field wires to the alternator had broken inside the insulation and the alternator wasn't getting a "charge" signal. I knew from that experience that these cars have VERY low draw when just driving - I made it to Carlisle and back 3x, with no charging - so I knew I could make it home today if I needed to. So, I unplugged the field wire from the alternator....and the ammeter went to center and stayed there.
OK. So that's good.
Left the dash apart, windows up, eagle eye out for wisps of smoke, sniffer working overtime to make sure no "fresh" burning smell was happening. Drove home. Drove right to the workshop, left it idling, and grabbed my multimeter.
Field wire unhooked, 12.41v at idle at the battery terminals; no change when revving the engine (makes sense, since the field wire was still unhooked).
Plugged the field wire back in, immediately heard a drag on the engine and the multimeter jumped to 14.85v at idle. Revved the engine in neutral and it SPIKED - I got off the throttle when it crossed 18v, and unhooked that field wire again. Back to 12ish at idle. Took the car down to the garage, and parked it. For the winter, probably.
So, I'm going to start with a new alternator. It looks like my alternator crapped out and is overcharging - but I'm going to be testing the new one on install anyway, to make sure something else isn't acting up. (*edit - I'll check the voltage regulator as well, first, since I have spares) AND, I'm going to pull the cluster back out to check the wiring, and make sure nothing was seriously damaged (and order replacement harness(es) as needed). And, while I'm in there, I may well pull the heater box and do some work in there - get the fan working again, replace the heater core and HCV, and replace the evaporator. I haven't worried about it since I didn't really want to take the dash apart, but since the car is forcing my hand now....
What a day.
