Gauge Reads "0" When Engine Running

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1991 GMC Pickup, 1991 GMC Cab & Chassis, 1991 GMC C3500 HD, 1991 Chevrolet Pickup, and 1991 Chevrolet Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

Check oil level, and add oil if necessary. Test oil pressure using manual gauge and adapter. If oil pressure reading is good on manual gauge tester, check for grounded gauge circuit by disconnecting lead at sending unit.
Turn ignition on. Oil pressure gauge should now read 80. If gauge stays at zero, disconnect lead from gauge. If gauge now reads 80, find and repair short to ground between gauge and sending unit. If gauge still reads zero, replace gauge, and test oil pressure gauge sending unit resistance. See OIL PRESSURE GAUGE SENDING UNIT RESISTANCE table. Replace sending unit if it reads one ohm with engine running.

OIL PRESSURE GAUGE SENDING UNIT RESISTANCE

Position

Ohms

Engine Off

Engine Running

44 ⁽¹⁾

⁽¹⁾	With oil pressure at about 40 psi (2.8 kg/cm² ).