Temperature Gauge Calibration Test

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

Test equipment consists of a 10 ohm resistor to check gauge calibration for correct high readings, and a 73 ohm resistor to check for correct low scale readings.

Disconnect lead from gauge at sender unit, connect resistor between gauge lead and ground. Turn ignition on; with 10 ohm resistor, gauge should read within 1/2 pointer width on either side of "H" graduation. With 73 ohm resistor, gauge should read within 1/2 pointer width on either side of "C" graduation.

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.