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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage
Conditions for Running the DTC
| • | The engine run time is more than 3 seconds. |
| OR |
| • | The ignition is ON and the intake air temperature (IAT) is less than 90°C (194°F). |
| • | The DTC runs continuously when either condition above is met. |
Conditions for Setting the DTC
The PCM detects that the ECT sensor parameter is more than 139°C (282°F) intermittently for more than 2.5 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. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Observe the DTC information with a scan tool. Is DTC P0117 set? | Go to DTC P0117 | Go to Step 3 |
3 | Observe the engine coolant temperature (ECT) sensor parameter while moving the ECT sensor connector and the powertrain control module (PCM) connector. Does the scan tool indicate an abrupt change in value? | Go to Step 5 | Go to Step 4 |
4 | Observe the ECT 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 6 | Go to Step 7 |
5 | Repair the connector or terminal, as necessary. Refer to Circuit Testing and Connector Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | Go to Intermittent Conditions |
6 | Repair the harness or wiring, as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | Go to Intermittent Conditions |
7 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 8 |
8 | Observe the Capture Info. with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
