Gauge Indicates Zero When Engine Running

Check oil level. Add oil if necessary. Measure oil pressure with manual gauge. If oil pressure is okay, check for grounded gauge circuit by unplugging wire at sending unit.
Turn ignition on. Oil pressure gauge should indicate 80 psi. If gauge stays at zero, disconnect wire from gauge. If gauge now indicates 80 psi, find and repair short to ground between gauge and sending unit.
If gauge still indicates zero, replace gauge. Measure oil pressure gauge sending unit resistance. See the OIL PRESSURE GAUGE SENDING UNIT RESISTANCE table. Replace sending unit if it indicates one ohm with engine running.

OIL PRESSURE GAUGE SENDING UNIT RESISTANCE

Position

Ohms

Engine Off

Engine Running

⁽¹⁾ 44

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