Circuit Description
The engine coolant temperature (ECT) sensor is a variable resistor, that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the ECT signal circuit and a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an excessively low ECT signal voltage, which is a high temperature indication, DTC P1114 sets.
Conditions for Running the DTC
Engine run time is more than 5 seconds.
Conditions for Setting the DTC
The PCM detects an intermittent high ECT sensor temperature while the engine is running and run time exceeds five seconds.
Action Taken When the DTC Sets
| • | The control module stores the DTC in history after the first failure but will not illuminate the malfunction indicator lamp (MIL). |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. |
| • | A warm-up cycle occurs when the 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. |
Diagnostic Aids
| • | An ECT sensor or PCM which is intermittently shorted, open, or skewed is possible yet very unlikely. |
| • | An intermittent short to ground in the ECT sensor signal circuit could result in a DTC P1114. If the low ECT voltage (high temperature) reading is present, additional sensor circuit voltage codes could be set. Refer to any non-intermittent DTCs that are set. |
| • | Test the coolant sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in driveability complaints. Refer to Temperature Versus Resistance . |
| • | If an intermittent condition is suspected refer to Intermittent Conditions . |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Does the scan tool indicate that DTC P0117 also failed? | Go to DTC P0117 | Go to Step 3 |
3 |
Does the scan tool indicate an abrupt change in value? | Go to Step 6 | Go to Step 4 |
4 |
Does the scan tool indicate an abrupt change in value? | Go to Step 7 | Go to Step 5 |
Does the DTC set ? | Go to Diagnostic Aids | System OK | |
6 | Repair the connector/terminal as necessary. Refer to Circuit Testing and Connector Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | -- |
7 | Repair the harness/wiring as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | -- |
8 |
Does the DTC set? | Go to Step 2 | Go to Step 9 |
9 | With a scan tool observe the stored information in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
