Code 09: Engine Coolant Temperature (ECT) Sensor Circuit
- Check ECT sensor connector for poor connection. Clean or repair connector as necessary. If connector is okay, go to next step.
- Using an ohmmeter, check continuity of Blue/White wire between ECT sensor connector and terminal No. 9 of ECM C249 (26-pin) connector. Check continuity of Black/Red wire between ECT sensor connector and terminal No. 15 of ECM C249 (26-pin) connector. If continuity exists in both readings, go to next step. If continuity does not exist in one or both readings, locate and repair open in Blue/White wire and/or Black/Red wire between ECT sensor connector and ECM connector.
- Disconnect ECT sensor connector. Measure resistance between sensor terminals at specified temperature. See ECT SENSOR RESISTANCE
. If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor.ECT SENSOR RESISTANCE
Temperature - °F (°C) Ohms 176 (80) 317-325 68 (20) 2200-2700 -4 (-20) 14,600-17,800 - Perform after-repair procedure. See AFTER-REPAIR PROCEDURE . If Code 09 is still present, go to next step. If Code 09 is not present, no problem is indicated. ECT sensor and related circuits are okay at this time.
- Check voltage at specified terminals of ECM C249 (26-pin) connector. See TESTING ECT SENSOR CIRCUIT . If all voltage readings are as specified, replace ECM. If any voltage reading is not as specified, locate and repair short in appropriate wire between ECM connector and ECT sensor connector.
TESTING ECT SENSOR CIRCUITS
| Measure Voltage At ECM C249 Connector Terminal | Volts | |
|---|---|---|
| No. 9 (Blue/White Wire) | ||
| Coolant Temperature At 68°F (20°C) | About 2.5 | |
| Coolant At Normal Operating Temperature | Less Than 0.5 | |
| No. 15 (Black/Red Wire) | Zero | |