Tachmeter Electrical Repair
We had a car come in with a partially dead tachometer. All guages were inoperable. New part was over 1000 CHf ($1,000). A tech just plugged in a new tacho and it failed too. A Grand up in smoke. Talked the boss into letting me take a look at the new cluster.
I found several overheated and burnt circuit traces. One of which supplied power to the guage servos. Was able to facilitate repairing the circuit board.
Normally, this should never have happened. Before reinstalling the tach I inspected the wiring harness. Found extreem oxidation inside a large wiring haness connector in the engine bay (no picts). This short cause the tacho to fail.
Repaired connector and reinstalled tacho. All worked perfectly and saved the shop a grand. :)