STEP 1. Using scan tool (M.U.T.-IIISE), check data list item 6: Engine Coolant Temperature Sensor.
STEP 2. Measure the sensor output voltage at engine coolant temperature sensor connector.
(1) Disconnect the engine coolant temperature sensor connector and connect the test harness special tool MB991658 between the separated connectors.
(2) Turn on the power supply mode of the electric motor switch.
(3) Measure the voltage between terminal WTS and ground.- When engine coolant temperature is -20°C (-4°F), voltage should be between 3.9 and 4.5 volts.
- When engine coolant temperature is 0°C (32°F), voltage should be between 3.2 and 3.8 volts.
- When engine coolant temperature is 20°C (68°F), voltage should be between 2.3 and 2.9 volts.
- When engine coolant temperature is 40°C (104°F), voltage should be between 1.3 and 1.9 volts.
- When engine coolant temperature is 60°C (140°F), voltage should be between 0.7 and 1.3 volts.
- When engine coolant temperature is 80°C (176°F), voltage should be between 0.3 and 0.9 volt.
(4) Turn off the power supply mode of the electric motor switch.
Is the measured voltage within the specified range?
Go to Step 3. Go to Step 4.
STEP 3. Using scan tool (M.U.T.-IIISE), check data list item 6: Engine Coolant Temperature Sensor.
STEP 4. Measure the sensor supply voltage at engine coolant temperature sensor harness side connector.
(1) Disconnect the engine coolant temperature sensor connector and measure at the harness side.
(2) Turn on the power supply mode of the electric motor switch.
(3) Measure the voltage between terminal WTS and ground.- Voltage should be between 4.5 and 4.9 volts.
(4) Turn off the power supply mode of the electric motor switch.
Is the measured voltage between 4.5 and 4.9 volts?
Go to Step 5. Replace the ECM (Refer to Removal and Installation ). Then go to Step 9.
STEP 5. Check the continuity at engine coolant temperature sensor harness side connector.
STEP 6. Check of harness damage in WTSE line between engine coolant temperature sensor connector and ECM connector.
STEP 7. Check the engine coolant temperature sensor.
STEP 8. Check of harness damage in WTS line between engine coolant temperature sensor connector and ECM connector.
STEP 9. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2 . (2) Check the diagnostic trouble code (DTC).
Is DTC P0125 set?
Retry the troubleshooting. The inspection is complete.