Oil Pressure Gauge Calibration Test

When instrument voltage regulator or gauge is suspected of being out of calibration, having a fluctuating movement, or high or low pressure, both the gauge and IVR must be tested simultaneously. This test is done on the vehicle.

Test equipment consists of a 22.8 ohm resistor to check gauge calibration for correct mid scale readings, and a 73 ohm resistor to check for low scale readings.

Disconnect lead from gauge at sender unit, connect resistor between gauge lead and ground. Turn on ignition. With the 22.8 ohm resistor, gauge should show a midscale reading.

With the 73 ohm resistor, gauge should show a low scale reading. If gauge does not perform as prescribed, replace IVR and retest. If gauge now (with new IVR) reads correctly, problem is solved. If gauge is still out of calibration, it is defective and must be replaced.