From FSM: This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the PCM,
Over the Programmable Communications Interface (PCI) data bus.
The engine coolant temperature gauge is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output
(run-start) circuit whenever the ignition switch is in the On or Start positions.
The cluster is programmed to move the gauge needle back to the low end of the scale after the ignition switch is turned to the Off position.
The instrument cluster circuitry controls the gauge needle position.
Actuator Test - Each time the cluster is put through the actuator test, the engine coolant temperature gauge needle will be swept to several gauge calibration points on the gauge scale in a prescribed sequence in order to confirm the functionality of the gauge and the cluster control circuitry.
The PCM continually monitors the engine coolant temperature sensor to determine the engine operating temperature. The PCM then sends the proper engine coolant temperature messages to the instrument cluster.
For further diagnosis of the engine coolant temperature gauge or the instrument cluster
circuitry that controls the gauge, (Refer to 8 - ELECTRICAL/ INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING)