Oil pressure sending unit / switch ?'s...

[rd122481]

My 2001 Tahoe will not register ANY oil pressure at all on the instrument cluster. The engine sounds perfectly healthy, except for the cold start up piston slap which is normal. I am guessing it is the sensor / switch that has gone bad because when I disconnect the signal wire my oil pressure gauge will peg to the maximum without the engine even running. My question is this: How much voltage should I be reading at the signal wire? Should I be seeing battery voltage? At the moment I am seeing about 8.8 - 8.9 volts.

Also...
Do I HAVE to purchase the special socket tool for this job or is there something else that I can use?

Thanks!!

 

[Dbowl]

27mm deep well works fine.

Not sure about the voltage.

as I note I picked up the replacement part from amazon for like 34$.