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Home >> Mitsubishi >> 2002 >> Lancer LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0116: Engine Coolant Temperature Circuit Range/Performance Problem >> Diagnostic Procedure

Diagnostic Procedure

CAUTION: To prevent damage to scan tool, always turn ignition switch to LOCK position before connecting or disconnecting scan tool.
  1. Connect scan tool to data link connector. Turn ignition on. Set scan tool to the data reading mode for data list item 21: ENGINE COOLANT TEMPERATURE SENSOR. The engine coolant temperature and temperature shown with the scan tool should approximately match. Turn ignition switch to LOCK position. If sensor is operating properly, malfunction is intermittent. If sensor is not operating properly, go to next step.
  2. Do not disconnect ECT harness connector. Turn ignition on. Using a DVOM, measure voltage between sensor harness connector terminal No. 1 (Yellow/White wire) and ground by backprobing. See ENGINE COOLANT TEMPERATURE SENSOR VOLTAGE  table. If voltage is as specified, go to next step. If voltage is not as specified, go to step  5 .
    ENGINE COOLANT TEMPERATURE SENSOR VOLTAGE

    Temperature - °F (°C) Voltage
    -4 (-20) 3.9-4.5
    32 (0) 3.2-3.8
    68 (20) 2.3-2.9
    104 (40) 1.3-1.9
    140 (60) 0.7-1.3
    176 (80) 0.3-0.9
  3. Turn ignition off. Check ECT sensor harness connector for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is okay, go to next step.
  4. Connect scan tool to data link connector. Turn ignition on. Set scan tool to the data reading mode for data list item 21: ENGINE COOLANT TEMPERATURE SENSOR. The engine coolant temperature and temperature shown with the scan tool should approximately match. Turn ignition switch to LOCK position. If sensor is not operating properly, replace ECM (M/T) or PCM (A/T). After replacing ECM or PCM, go to step  14 . If sensor is operating properly, malfunction is intermittent.
  5. Check ECT sensor harness connector for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, go to next step.
  6. Disconnect ECT sensor harness connector. Turn ignition on. Measure voltage between ECT sensor harness connector terminal No. 1 (Yellow/White wire) and ground. Voltage should be 4.5-4.9 volts. Turn ignition switch to LOCK position. If voltage is not as specified, go to next step. If voltage is as specified, go to step  8 .
  7. Check ECM harness connector C-115 (M/T) or PCM harness connector C-118 (A/T) for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, replace ECM or PCM. After replacing ECM or PCM, go to step  14 .
  8. Check continuity between ECT sensor terminal No. 2 (Black wire) and ground. Resistance should be less than 2 ohms. If continuity is not as specified, go to next step. If continuity is as specified, go to step  11 .
  9. Check ECM harness connector C-115 (M/T) or PCM harness connector C-118 at (A/T) for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, go to next step.
  10. Check for harness damage between ECT sensor harness connector terminal No. 2 and ECM harness connector C-115 terminal No. 92 (M/T) or PCM harness connector C-118 terminal No. 57 (A/T). Repair as necessary. After repairs, go to step  14 . If wiring harness is in good condition, replace ECM or PCM. After replacing ECM or PCM, go to step  14 .
  11. Check ECT sensor. Disconnect ECT sensor harness connector. Remove ECT sensor from engine. With the temperature sensing portion of engine coolant temperature sensor immersed in hot water, check resistance. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE  table. If resistance is as specified, replace ECM or PCM. After replacing ECM or PCM, go to step  14 . If resistance is not as specified, replace ECT sensor. Apply 3M AAD (8731) on the thread section of ECT sensor. Install ECT sensor and tighten to 15-29 ft. lbs. (19-39 N.m). After installing ECT sensor, go to step  14 .
    ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE

    Temperature °F (°C) k/Ohms
    -4 (-20) 14-17
    32 (0) 5.1 -6.5
    68 (20) 2.1 -2.7
    104 (40) 0.9 - 1.3
    140 (60) 0.48 -0.68
    176 (80) 0.26 -0.36
  12. Check ECM harness connector C-115 (M/T) or PCM harness connector C-118 (A/T) for damage. Repair or replace as necessary. After repairs, go to step  14 . If connector is in good condition, go to next step.
  13. Check for harness damage between ECT sensor harness connector terminal No. 1 and ECM harness connector C-115 terminal No. 83 (M/T) or PCM harness connector C-118 terminal No. 44 (A/T). Repair as necessary. After repairs, go to next step. If wiring harness is in good condition, replace ECM or PCM. After replacing ECM or PCM, go to next step.
  14. Test the OBD-II drive cycle. Carry out a test drive with the drive cycle pattern. See OTHER MONITOR  under VERIFYING REPAIRS. Check for DTCs. If DTC P0116 is output, repeat diagnosis. If DTC P0116 is not output, inspection is complete.
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