smoking tachometer circuit board

[80convertible]

Started car up today and saw smoke coming from behind tachometer. I immediately shut the car off. After a quick inspection under the hood, I turned the ignition switch to accessory...no power at all...dead. Pulled tach and found blackened tach circuit board. The circuit board is still functional as I checked continuity with my meter. I can see no other evidence of bad/burnt wiring and no fuses are blown. I had not touched any of the electronics since driving last weekend after installing a new radiator. I had been installing power door lock actuators before my drive last week. No problems with the electrical then. I did notice after the smoke today that the driver side door lock switch wiring was touching metal on the door. But the door lock switch and the tach are not on the same circuit. I checked the battery and voltage is at 12.30. I had been charging it for about an hour before I tried to start the car. I also checked the fusible links to see if they blew...they have continuity. I have not reinstalled the batter again today...don't want to burn anything up. I have no idea what caused the tach circuit board to heat up or what caused a total power loss. I could really use some suggestions!

 

[mike weyman]

I think its just a coincidence, its nothing rare for a c3 to burn up the tach circuit.put the battery back in and retry.the most youll do is blow a fuse. mike

 

[Bob Chadwick]

. I did notice after the smoke today that the driver side door lock switch wiring was touching metal on the door. But the door lock switch and the tach are not on the same circuit.

I lost my power windows and gauges on my 77 this Summer. I think water got into the door as I was washing it. Turned out to be the 10 amp gauge fuse. At least on the 77 they do have some common wires.

 

[80convertible]

I checked the fuses including the fusible links and nothing is blown. I too thought maybe it is a coincidence. The fact that I can't find a blown fuse is was adds to the mystery.