Chevrolet Repair: 1997 6.5TD Lift pump oil pressure switch, oil pressure switch, engine oil pressure

Question
The three pin connector to the oil pressure switch (part of the lift pump control circuitry)has an orange wire with +12volts, then two other wires (can't tell color) one maybe gray the other tan. According to the GM manual one wire is controlled by the pump relay and the other goes directly to the pump. When the truck is idling what voltage levels should I see on these two pins? Thank you.

Answer
That oil pressure switch is a paralell system to the relay. It isn't controlled by the relay.
As long as there is engine oil pressure, that switch will supply voltage to the pump, no matter what the relay is, or isn't doing.
The orange wire is battery voltage. I believe the larger of the other two is the one to the pump, and the other is from the oil pressure guage.
To test the switch, the relay will need to be disconnected, since the wires to the pump from both the relay, and the switch, are connected together, and if one or the other system is working, there will be battery voltage on both wires to the pump.
So with the engine running, disconnect the relay, and see if the pump keeps running.

Van