Coolant Temperature Telltale

The Coolant Temp telltale is used to alert the driver that the engine may be in an overheated condition. The BCM controls the Coolant Temp telltale by monitoring the temperature sent over the CAN link from the ECM. The BCM will send a message to the I/P cluster over the Class II link to turn On the telltale when the ECT it received from the ECM is between 117°C (242°F) and 128°C (262°F). If a high temp/low voltage fault exists in the ECT sensor circuit, the signal is considered invalid and the Coolant Temp telltale will NOT be illuminated. The Malfunction Indicator Lamp (MIL) and cooling fan relay will be commanded On, however.