I do know that. I bought an IVR to replace that component while I’m at it.
So I disconnected the temp sender and grounded it. Temp gauge didn’t move, so I suspect the gauge is bad. Curiously when I grounded the temp wire, the oil gauge pegged full. I imagine that’s because both of these gauges are powered by that internal voltage regulator?
Nope, grounding the purple temp sender wire should have no effect on another gauge. Oil gauge sender wire is gray. I suspect it may be melted to the purple wire somewhere in the harness.