| CAUTION | If ECM replacement is instructed in following tests, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Note. If DTCs P0100, P0101, P0110, P0115 and P0120 are output together, inspect ECM E2 circuit (sensor ground) between terminal No. 18 (Brown wire) at ECM harness connector E4 and splice E2. Repair as necessary. See WIRING DIAGRAMS article.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
ECT sensor is a thermistor sensor which monitors engine coolant temperature. DTC is set when ECM detects an open or short in ECT sensor circuit. Possible causes are
- ECT sensor circuit is open or shorted.
- Defective ECT sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0115, use scan tool to access CURRENT DATA to confirm engine coolant temperature. If ECT sensor value displayed on scan tool is always -40°F (-40°C), ECT sensor circuit may be open. If ECT sensor value displayed on scan tool is always 284°F (140°C), ECT sensor circuit may be shorted. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.