Coolant Temperature Telltale

The Coolant Temperature telltale is used to alert the driver that the engine may be in an overheated condition. The ECM controls the Coolant Temperature telltale by sending a message to the BCM, which sends a message to the I/P cluster over the CAN link to turn On the telltale. The ECM will send the message when the ECT sensor reading is above 140°C (284°F). If this condition exists, the ECM will set DTC P0117. If a high temp/low voltage fault exists in the ECT sensor circuit, the signal is considered invalid and the Coolant Temperature telltale will NOT be illuminated. The cooling fans will be commanded On high.