P1114

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Engine Coolant Temperature (ECT) sensor is a thermistor immersed in the intake manifold cooling system passage. The Vehicle Control Module (VCM) applies a voltage on the 5 volt reference circuit to the sensor. When the engine is cold, the sensor (thermistor) resistance is high; therefore, the VCM senses a high signal voltage, and the VCM indicates the coolant temperature. As the engine warms, the sensor resistance becomes less and the voltage drops indicating the high coolant temperature. At the normal engine operating temperature (85°C to 95°C), the voltage measures about 1.5 to 2.0 volts.

CONDITIONS FOR SETTING THE DTC

Engine run time is greater than 5 seconds.

ACTION TAKEN WHEN THE DTC SETS

The VCM stores the DTC to the History if the VCM detects an intermittent problem.

CONDITIONS FOR CLEARING THE MIL/DTC

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 start-up 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

A poor connection or an open in the 5 volt reference circuit or the ECT sensor ground circuit results in a DTC P1115.

The scan tool displays the engine temperature in degrees centigrade. After the engine is started, the temperature should rise steadily to about 90°C then stabilize when the thermostat opens.

Use the Temperature vs. Resistance Value scale in order to test the coolant sensor at various temperature levels in order to evaluate the possibility of a skewed or mis-scaled sensor. A skewed sensor could result in poor driveability complaints. 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, engine coolant voltage will be less than 0.82 volts.

3. This test simulates a DTC P0118. If the VCM recognizes the high signal voltage (high temperature), and the scan tool reads 4.9 volts or above, the VCM and wiring are OK.

4. This test will determine if the 5 volt reference circuit is open. There should be 5 volts present at sensor connector if measured with a J 39200 Digital Multimeter (DMM). This will determine if there is a wiring problem or a faulty VCM.