Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0117: Engine Coolant Temperature (ECT) Sensor Circuit Low VoltageDTC P0118 : Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
DTC P1114 : Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage
DTC P1115 : Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
ECT Sensor Signal | P0117 | P0118 | P0118 | P0118 | P0116, P0125-L32 only, P0128 |
Low Reference | -- | P0118 | P0118 | P0118 | P0125-L32 only, P0128 |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
ECT Sensor Signal | -39°C to +120°C (-38°F to +248°F) | 150°C (303°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit/System Description
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The control module 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 decreases. With high sensor resistance, the control module detects a high voltage on the ECT signal circuit. With lower sensor resistance, the control module detects a lower voltage on the ECT signal circuit.
Conditions for Running the DTC
P0117 or P1114
| • | The engine run time is more than 3 seconds. |
| OR |
| • | The ignition is ON and the IAT parameter is less than 90°C (194°F). |
| • | The diagnostic runs continuously when the above conditions are met. |
P0118 or P1115
| • | The engine is running for more than 30 seconds. |
| OR |
| • | The ignition is ON and the IAT parameter is more than 0°C (32°F). |
| • | The diagnostic runs continuously when the above conditions are met. |
Conditions for Setting the DTC
P0117
The control module detects that the ECT sensor parameter is more than 139°C (282°F) for more than 24 seconds.
P0118
The control module detects that the ECT sensor parameter is less than -37°C (-35°F) for more than 24 seconds.
P1114
The control module detects that the ECT sensor parameter is more than 139°C (282°F) intermittently for more than 20 seconds.
P1115
The control module detects that the ECT sensor parameter is less than -37°C (-35°F) intermittently for more than 20 seconds.
Action Taken When the DTC Sets
P0117 and P0118
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
P1114 and P1115
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The 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 (DIC), if equipped, may display a message. |
Conditions for Clearing the DTC
P0117 or P0118
| • | The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
P1114 or P1115
| • | 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 overheating condition may cause this DTC to set. |
| • | After starting the engine, the ECT sensor temperature should rise steadily to about 90°C (194°F) then stabilize after the thermostat opens. |
| • | If a short to a separate voltage source occurs, this DTC may set and damage the ECT sensor. |
| • | If an intermittent condition is suspected, refer to Testing for Intermittent Conditions and Poor Connections . |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Circuit/System Testing
Important:
• If P0117 and P0118 are both set, diagnose P0118 first. • The cooling fans are commanded ON when certain DTCs are set. • If a short to voltage occurs, the ECT sensor may be damaged.
P0117
Ignition ON, engine OFF, disconnect the ECT sensor and observe the ECT parameter for -38°C (-36°F).
| ⇒ | If over -38°C (-36°F), test the signal circuit of the ECT sensor for a short to ground, or a short to any low reference circuit. If the ECT circuit test OK, then replace the ECT sensor. |
| ⇒ | If under -38°C (-36°F), test for an intermittent and for a poor connection at the ECT sensor. If the ECT circuit tests OK, then replace the control module. |
P0118
- With the ignition ON, engine OFF, disconnect the ECT sensor and measure for 5.2 volts from the signal circuit of the ECT sensor to a good round with a DMM.
- With the ignition ON, engine OFF
- Connect a 3A jumper wire between the signal circuit of the ECT sensor and the low reference circuit.
- Observe the ECT parameter with a scan tool for 139°C (282°F).
- Connect a 3A jumper wire between the signal circuit of the ECT sensor and a good ground.
- Observe the ECT parameter with a scan tool for 139°C (282°F).
| ⇒ | If over 5.2 volts, then test the ECT signal circuit for a short to voltage, an intermittent and for a poor connection at the control module. If all test OK, then replace the control module. |
| ⇒ | If under 4.8 volts, then test the signal circuit of the ECT sensor for high resistance, an open, or a short to any 5-volt reference circuit. If tests OK, then replace the ECT sensor. |
| ⇒ | If more then specified value, then test the ECT signal circuit for a short to any 5-volt reference circuit, faulty connection at control module. If circuits test OK, then replace the ECT sensor. |
| ⇒ | If more than the specified value, then test the ECT low reference circuit for high resistance or an open. Test for a faulty connection at the control module, or a faulty control module. If the circuit tests OK, then replace the control module. |
P1114 or P1115
- Observe the engine coolant temperature (ECT) sensor parameter on the scan tool, while moving the ECT sensor connector and the control module connector. Is there an abrupt change indicated on the scan tool?
- If everything checks out, then refer to Testing for Intermittent Conditions and Poor Connections .
| ⇒ | If change, then repair the connector or terminal as necessary. |
| ⇒ | If no change, observe the engine coolant temperature (ECT) sensor parameter on the scan tool, while moving the wiring harness at the ECT sensor and the control module. If there is a change on the scan tool, then repair the wiring as necessary. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for PCM replacement, setup, and programming |
