Coolant Temperature Gauge Signal

Coolant Temperature Gauge Signal
The ECM controls the temperature gauge in the instrument cluster. The ECM sends a coolant temperature signal to the temperature gauge in the instrument cluster in the form of a PWM square wave signal.

The frequency of the signal determines the level of the temperature gauge.

Conditions
The ECM operates the PWM signal under the following parameters:
^ -40 °C (-40 °F) = a pulse width of 768 micros.
^ 140 °C (284 °F) = a pulse width of 4848 micros.

Function
The coolant temperature signal is an output from the ECM to the instrument cluster. The coolant temperature signal is generated via pin 44 of connector C0636 of the ECM.

The coolant temperature signal can fail in the following ways:
^ Wiring short circuit to vehicle supply.
^ Wiring short circuit to vehicle earth.
^ Wiring open circuit.

In the event of a coolant temperature signal failure any of the following symptoms may be observed:
^ Coolant temperature gauge will read cold at all times.
^ Coolant temperature warning lamp remains on at all times.