P0118
Fuel System - Troubleshooting - P0118Component Location:
GENERAL DESCRIPTION
The Engine Coolant Temperature Sensor (ECTS) is located in the engine coolant passage of the cylinder head for detecting the engine coolant temperature. The ECTS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the ECTS decreases as the temperature increases, and increases as the temperature decreases. The reference 5 V in the PCM is supplied to the ECTS via a resistor in the PCM. That is, the resistor in the PCM and the thermistor in the ECTS are connected in series. When the resistance value of the thermistor in the ECTS changes according to the engine coolant temperature, the output voltage also changes. During cold engine operation the PCM increases the fuel injection duration and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve driveablity.
DTC DESCRIPTION
PCM sets DTC P0118 if the PCM detects signal voltage higher than the possible range of a properly operating ECTS.
DTC Detecting Condition:
MONITOR DTC STATUS
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Press F5(INFO) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions Read "DTC Status" parameter.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History(Not Present) fault"?
NOTE:
1. History (Not Present) fault : DTC occurred but has been cleared.
2. Present fault : DTC is occurring at present time.
YES - Fault is intermittent caused by poor contact in the sensor's and/or the PCM's connector, which was repaired but PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Monitor Scantool Data" procedure.
MONITOR SCANTOOL DATA
1. Ignition "ON" & Engine "OFF".
2. Disconnect ECTS connector.
3. Connect Scantool and monitor the "COOLANT TEMP. SNSR(V)" parameter on the Scantool data list.
4. Jumper the terminals 1 and 3 of the sensor harness connector together.
Specification : Approx. 0 V
5. Is ECTS parameter near the specified value?
YES - Possibility of sensor malfunction. Go to "Component Inspection" procedure.
NO - Go to next step.
6. Jumper the terminal 1 of the sensor harness connector to chassis ground.
7. Read the "COOLANT TEMP. SNSR(V)" parameter on the Scantool.
8. Is displayed ECT data near the specified value.?
YES - Possibility of open in ECTS ground circuit Go to "Ground Circuit Inspection" procedure.
NO - Possibility of open or short to battery in ECTS signal circuit. Go to "Signal Circuit Inspection" procedure.
GROUND CIRCUIT INSPECTION
1. Ignition "OFF".
2. Disconnect PCM connector.
3. Measure resistance between terminals 3 of the sensor harness connector and 73 of the PCM harness connector.
Specification : Approx. 0 Ohm
4. Is resistance within the specification?
YES - Go to "Terminal and connector Inspection" procedure.
NO - Repair open circuit and go to "Verification of Vehicle Repair" procedure.
SIGNAL CIRCUIT INSPECTION
1. Check for open in signal circuit.
1. Measure resistance between terminals 1 of the sensor harness connector and 31 of the PCM harness connector.
Specification : Approx. 0 Ohm
2. Is resistance within the specification?
YES - Go to next step
NO - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to battery in signal circuit.
1. Ignition "ON" & Engine "OFF".
2. Measure voltage between terminals 1 of the sensor harness connector and 31 of the PCM harness connector.
Specification : Approx. 0 V
3. Is voltage within the specification?
YES - Go to "Terminal and Connector Inspection" procedure.
NO - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Component Inspection" procedure.
Specification:
COMPONENT INSPECTION
1. Ignition "OFF".
2. Measure resistance between terminals 1 and 3 of the sensor connector(Component side).
3. Is resistance within the specification?
YES - Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Check ECTS for contamination, deterioration, or damage. Substitute with a known-good ECTS and check for proper operation. If the problem is corrected, replace ECTS and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
2. Press F5(INFO) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
3. Read "DTC Status" parameter
4. Is parameter displayed "History(Not Present) fault"?
YES - System performing to specification at this time. Clear the DTC
NO - Go to the applicable troubleshooting procedure.
Schematic Diagram:
