Diagnostic Procedure

CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to "GROUND INSPECTION ".
  
  Fig 1: Checking Ground Connections
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: GO TO 2.
- NG: Repair or replace ground connections.
CHECK ECT SENSOR POWER SUPPLY CIRCUIT
1. Disconnect engine coolant temperature (ECT) sensor harness connector.
2. Turn ignition switch ON.
  
  Fig 2: Disconnecting Engine Coolant Temperature (ECT) Sensor Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check voltage between ECT sensor terminal 1 and ground with CONSULT-II or tester.
  - Voltage: Approximately 5V
  Fig 3: Checking ECT Sensor Power Supply Circuit
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: GO TO 3.
- NG: Repair open circuit or short to ground or short to power in harness or connectors.
CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
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 5.
- NG: GO TO 4.
DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E19, F33
- Harness for open and short between ECT sensor and ECM
- Harness for open and 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 6.
- NG: Replace engine coolant temperature sensor.
CHECK INTERMITTENT INCIDENT
Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".
- : INSPECTION END