Circuit Description

Engine Coolant Temperature (ECT) sensor is a thermistor that monitors coolant temperature. See Fig 1. If DTC is set, ECM will operate in fail-safe mode. During fail-safe mode, engine coolant temperature is fixed at 176°F (80°C). DTC is set when ECM detects an open or short in ECT sensor circuit. Possible causes are:

• Open or short in ECT sensor circuit.
• Faulty ECT sensor.
• Faulty ECM.

Fig 1: Identifying Engine Coolant Temperature Sensor Circuits

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