Diagnostic Procedure

CHECK ETC SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect engine coolant temperature (ECT) sensor harness connector.
  
  Fig 1: Disconnecting Engine Coolant Temperature (ECT) Sensor Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Turn ignition switch ON.
4. Check voltage between ECT terminal 1 and ground with CONSULT-II or tester.
  - Voltage: Approximately 5V
OK or NG
- OK : GO TO 2.
- NG : Repair open circuit or short to ground or short to power in harness or connectors.
CHECK ETC SENSOR GROUND CIRCUIT FOR OPEN AND SHORRT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect TCM harness connector.
4. Check harness continuity between ECT sensor terminal 2 and ECM terminal 67, TCM terminal 42. Refer to WIRING DIAGRAM .
  - Continuity should exist.
5. Also check harness for short to ground and short to power.
OK or NG
- OK : GO TO 4.
- NG : GO TO 3.
DETECT MALFUNCTIONING PART
Check the following.
- Harness for open or short between ECT sensor and ECM
- Harness for open or short between ECT sensor and TCM
  - : Repair open circuit or short to ground or short to power in harness or connectors.
CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to "COMPONENT INSPECTION ".

OK or NG
- OK : GO TO 5.
- NG : Replace ECT sensor.
CHECK INTERMITTENT INCIDENT
Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".
- : INSPECTION END