Circuit Description
The engine coolant temperature (ECT) sensor is a variable resistor, sometimes called a thermistor, that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the ECT signal 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
The engine run time is more than 3 seconds.
Conditions for Setting the DTC
The ECT sensor temperature is more than 139°C (282°F) for more than 10 seconds.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
| • | An intermittent short to ground in the ECT sensor signal circuit could result in a DTC P1114. If the low ECT voltage reading is present, additional sensor circuit voltage codes could be set. Refer to any non-intermittent DTCs that are set. |
| • | 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 sensor. A skewed sensor could result in poor 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 Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Is DTC P0117 set? | 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 | Observe the ECT sensor parameter with a scan tool while moving the wiring harness at the ECT sensor and the PCM. Does the scan tool indicate an abrupt change in value? | Go to Step 7 | Go to Step 5 |
Did the DTC fail this ignition? | Go to Diagnostic Aids | System OK | |
6 | Repair the connector and/or terminal as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | -- |
7 | Repair the harness and wiring as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | -- |
8 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 9 |
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
