P1115

DTC P1115 ECT Sensor CKT Intermittent High Voltage (1 Of 2):

DTC P1115 ECT Sensor CKT Intermittent High Voltage (2 Of 2):

ECT Sensor Circuit:

Circuit Description
The Engine Coolant Temperature (ECT) sensor is a thermistor immersed in the intake manifold cooling system passage. The ECT monitors the temperature of the engine coolant. The Vehicle Control Module (VCM) applies 5 volts to the sensor on the 5 volt reference circuit. When the coolant is cool, the resistance in the sensor measures high, and the VCM senses a high voltage signal. When the coolant temperature is warm, the sensor resistance measures low, and the VCM senses a low voltage signal. The DTC P1115 is a type D DTC.

Conditions For Setting The DTC
The DTC sets when the signal voltage indicates an engine coolant temperature voltage above 4.9 and the engine run time is greater than 5 seconds.

Action Taken When The DTC Sets
The VCM sets the DTC and turns on the Malfunction Indicator Lamp (MIL) when this DTC is reported and 1 failure has occurred.

Conditions For Clearing The MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.

Diagnostic Aids
A faulty 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 Temperature vs Resistance. Specifications

Test Description
The numbers below refer to the step numbers in the diagnostic table.

2. If the fault is present, the engine coolant temperature voltage measures greater than 4.9 volts.
3. This test simulates the conditions for a DTC P0117. If the VCM recognizes the grounded circuit (low voltage) and displays a low voltage, the VCM and the wiring are OK.
4. This test checks for an open or grounded signal sensor circuit. Also being checked are the ECT sensor ground circuit and the VCM.