I think my oil pressure switch on my 3.2 that is located on the top back of engine next to the tranny is bad.

So I am finally hooking up the wiring to my 4 gauge cluster gauge. I have the oil pressure gauge, oil temp gauge, fuel tank, and voltmeter working. The only problem now is the oil pressure switch "idiot" light not working. When I check the continuity of the green/red stripe wire from the 914 harness to the 1988 911 engine harness it checks out great. When I pull the wire off the oil pressure switch on the top of the 911 engine and ground it, and turn on the ignition the oil light lights right up on the gauge cluster and then goes off when I remove the ground.
When I plug the wire onto the oil pressure switch and turn on the ignition and start the car the light doesn't light up at all. How can you tell if the oil pressure switch is bad?

Thanks,
Buck

The oil pressure switch is a "normally closed" switch, meaning with engine off the oil pressure switch should connect directly to ground.

If you hook an ohm meter to the terminal on the switch and test the circuit to ground (engine case) you should get zero ohms or very close to zero.
When the engine is running and has oil pressure ( >7psi?) the switch will be open and no longer connect to ground.

Jim

Turn the key on and pull off the wire and touch it to the block. The light should come on.

If it turns on that way then you have a bad switch.

Edit: or maybe you've used so much Teflon tape on the threads that the switch can't ground?

Is your idiot light wire attached to a VDO combo pressure gauge/idiot light sender? Is that sender properly grounded?