Steam Gauge Failure Mode

[pa38112]

I have two failing Vans Steam Gauges: Oil temp and MAP. Both seem normal and then drop very quickly, then resume normal operation - except the oil temp gauge is registering lower than actual. Wiring and connections have been verified. My bet is that the gauges are the issue and not the senders, but does anyone have experience in the failure mode of the Vans Steam gauges?

[vic syracuse]

You most likely have a shared common ground for both of those and it is chafing or loose somewhere.

Vic

[pa38112]

No, the MAP has been acting up for months. Now the Oil Temp has started doing the same. They don't both drop at the same time.