LEMON Manuals: Even more car manuals for everyone
Home >> Mitsubishi >> 2003 >> Montero Limited >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0118: Engine Coolant Temperature Circuit High Input >> Diagnostic Procedure

Diagnostic Procedure

CAUTION: To prevent damage to scan tool (MB991502), always turn the ignition off before connecting or disconnecting it.
  1. Connect scan tool (MB991502) to the data link connector. Turn the ignition on. Set the scan tool to data reading mode for item 21: ENGINE COOLANT TEMPERATURE SENSOR. The engine coolant temperature and temperature shown with the scan tool should approximately match. Turn the ignition off. If the sensor is operating properly, it can be assumed that this malfunction is intermittent. Refer to INTERMITTENT DIAGNOSTIC TROUBLE CODES . If the sensor is malfunctioning, go to the next step.
  2. Check connector B-37 at the engine coolant temperature sensor for damage. If the connector is in good condition, go to the next step, otherwise, repair or replace it and proceed to step  11.
  3. Measure the sensor supply voltage at engine coolant temperature sensor harness side connector B-37. Disconnect the connector B-37 and measure at the harness side. Turn the ignition on. Measure the voltage between terminal No. 1 and ground. Voltage should be between 4.5-4.9 volts. Turn the ignition off. If the measured voltage is normal, proceed to step  7, otherwise, go to the next step.
  4. Measure the sensor supply voltage at PCM connector D-135 by backprobing. Do not disconnect the PCM connector D-135. Disconnect the engine coolant temperature sensor connector B-37. Turn the ignition on. Measure the voltage between terminal No. 98 and ground by backprobing. Voltage should be between 4.5-4.9volts. Turn the ignition off. If the voltage is normal, go to the next step, otherwise, proceed to step  6.
  5. Check connector D-135 at PCM for damage. If the connector is in good condition, repair harness wire between engine coolant temperature sensor connector B-37 (terminal No. 1) and PCM connector D-135 (terminal No. 98) (because of open circuit). If the connector is damaged, repair or replace it. Proceed to step  11.
  6. Check connector D-135 at PCM for damage. If the connector is in good condition, replace the PCM, otherwise, repair or replace the connector. Proceed to step  11.
  7. Check the continuity at engine coolant temperature sensor harness side connector B-37. Disconnect the connector B-37 and measure at the harness side. Check for continuity between terminal No. 2 and ground. Resistance should be 2 ohms. If the continuity is normal, proceed to step  10, otherwise, go to the next step.
  8. Check connector D-135 at PCM for damage. If the connector is in good condition, go to the next step, otherwise, repair or replace it and proceed to step  11.
  9. Check for open circuit between engine coolant temperature sensor connector B-37 (terminal No. 2) and PCM connector D-135 (terminal No. 96). If the harness wire is in good condition, replace the PCM, otherwise, repair the harness wire. Proceed to step  11.
  10. Check the engine coolant temperature sensor. Disconnect the engine coolant temperature sensor connector B-37. Remove the engine coolant temperature sensor. With the temperature sensing portion of engine coolant temperature sensor immersed in hot water, check resistance. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE . Apply 3M™ AAD part number 8731 or equivalent on the screw section of the engine coolant temperature sensor. Install the engine coolant temperature sensor, and tighten to the specified torque. Tightening torque: 15-29 ft. lb. (19-39 N.m). If the resistance is at the standard value, replace the PCM, otherwise, replace the engine coolant temperature sensor. Go to the next step.
  11. Carry out a test drive with the drive cycle pattern. See OTHER MONITOR  under OBD-II DRIVE CYCLES under DRIVE CYCLES. Check the diagnostic trouble codes. If DTC P0118 is set, retry the troubleshooting. If the DTC is absent, the inspection is complete.
scientia non olet · About LEMON Manuals