Diagnostic Procedures
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
- Retrieve DTCs. If DTC P0117 or P0118 is set, diagnose affected DTC(s) first. If DTC P0117 or P0118 is not set, go to next step.
- Check actual engine coolant temperature. Turn ignition on, with engine off. Observe ECT sensor parameter on scan tool. If scan tool displays ECT sensor value near actual coolant temperature, go to step 11. If scan tool does not display ECT sensor value near actual coolant temperature, go to next step.
- Disconnect ECT sensor harness connector. Observe ECT sensor parameter on scan tool. If scan tool displays -40°F (-40°C), go to next step. If scan tool does not display -40°F (-40°C), go to step 8.
- Connect a fused jumper wire between ECT sensor harness connector terminals. Observe ECT sensor parameter on scan tool. If scan tool displays 246°F (119°C), go to step 13. If scan tool does not display 246°F (119°C), go to next step.
- Connect a fused jumper wire between chassis ground and ECT sensor input circuit at ECT sensor harness connector. Observe ECT sensor parameter on scan tool. If scan tool displays 246°F (119°C), go to next step. If scan tool does not display 246°F (119°C), go to step 8.
- Repair open or high resistance in ECT sensor ground circuit between ECT sensor and PCM. After repairs, go to step 14. If circuit is okay, go to step 9.
- Turn ignition off. Disconnect PCM harness connectors. Check for a short or high resistance in ECT sensor input circuit between ECT sensor and PCM. Repair as necessary. After repairs, go to step 14. If circuit is okay, go to next step.
- Check for poor connections at ECT sensor and PCM. Repair as necessary. After repairs, go to step 14. If circuit is okay, go to next step.
- Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 14.
- Check engine cooling system for improper operation, faulty thermostat, low coolant level, and incorrect coolant. Repair as necessary. After repairs, go to step 14. If problem does not exist, go to next step.
- Turn ignition on, with engine off. Using scan tool, clear DTCs. Operate vehicle within FREEZE FRAME conditions. Retrieve DTCs. If DTC resets, go to next step. If DTC does not reset, see DIAGNOSTIC AIDS .
- Replace ECT sensor. After replacing sensor, go to next step.
- After repairs, clear DTCs. Operate vehicle within FREEZE FRAME conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).