P0117
Diagnostic Chart:
Wiring Diagram:
CIRCUIT DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is a thermistor which controls the signal voltage to the VCM. The VCM applies a voltage on a 5 volt reference circuit to the sensor. When the engine coolant is cold, the sensor's internal resistance is high resulting in a high voltage ECT Sensor Signal. As the engine coolant temperature increases, the sensor's internal resistance and ECT Sensor Signal decrease.
CONDITIONS FOR SETTING THE DTC
The following conditions will set the DTC:
The engine run time is greater than 5 seconds
ACTION TAKEN WHEN THE DTC SETS
The VCM turns the MIL ON when P0117 is reported and 1 failure has occurred.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The VCM turns the MIL OFF after 3 consecutive drive trips when the test has Run and Passed and not Failed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle).
^ Use the scan tool Clear Information function.
^ Disconnect the VCM battery feed for 30 seconds.
DIAGNOSTIC AIDS
After starting the engine, the temperature should rise steadily to about 90°C (194°F) then stabilize when the thermostat opens. A poor connection or an open in the 5 volt reference circuit or the sensor ground circuit results in a DTC P0117.
Use the Temperature vs. Resistance Value Table to test the coolant sensor at various temperature levels in order to evaluate the possibility of a skewed (mis-scaled) sensor. A skewed sensor could result in poor driveability concerns. Refer to Specifications / Electrical / Temperature vs Resistance.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. If the fault is still present, the engine coolant voltage will measure less than 0.25 volts.
3. This test simulates a DTC P0118. If the VCM recognizes the high signal voltage and the scan tool display reads 40 volts or more, the VCM and the wiring are okay.