• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Repair Verification provides an overview of each diagnostic category. |
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
---|---|---|---|---|---|
ECT Sensor Signal | P0117 | P0118 | P0118 | P0118 | P0116, P0125, P0128 |
Low Reference | -- | P0118 | P0118 | P0118, P0651 | P0125, P0128 |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Parameter Normal Range: -39 to +120°C (-38 to +248°F) | |||
ECT Sensor Signal | 150°C (302°F) | -40°C (-40™F) | -40°C (-40™F) |
Low Reference | -- | -40°C (-40™F) | -40°C (-40™F) |
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT sensor signal circuit and supplies a ground to the low reference circuit.
• | The engine is running for more than 10 seconds. |
OR |
• | The intake air temperature (IAT) is less than 50°C (122°F). |
• | The DTCs run continuously when the conditions are met. |
• | The engine running time is more than 10 seconds. |
• | The intake air temperature is more than 0°C (32°F). |
• | The DTCs runs continuously when the conditions are met. |
• | The ECM detects that the resistance of ECT sensor is less than 45 ohms, approximately 150°C (302°F). |
• | It occurs 5 times during the 6 tests. |
• | DTC P0117 sets when the above conditions are met. |
• | The ECM detects that the resistance of the ECT sensor is more than 450,000 ohms, about -60°C (-76°F). |
• | It occurs 5 times during the 6 tests. |
• | DTC P0118 is set when the above conditions are met. |
DTCs P0117 and P0118 are Type B DTCs.
DTCs P0117 and P0118 are Type B DTCs.
• | If the engine exists overheated conditions, DTC P0117 may set and verify the proper heat range and the operation of the thermostat. Refer to Thermostat Diagnosis . |
• | An ECT sensor signal circuit or low reference circuit that is shorted to another 5-volt reference circuit can cause a DTC P0118 to be set. |
Diagnostic Trouble Code (DTC) Type Definitions
Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.
Important: All electrical components and accessories must be turned OFF and allowed to power down.
⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit test normal, replace the ECM. |
⇒ | If the circuit test normal, replace the ECM. |
⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the ECM. |
Measure and record the resistance of the ECT sensor at various ambient temperatures, and then compare those measurements with the Temperature vs Resistance Table. Refer to Temperature Versus Resistance .
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |