Diagnostic Procedure

CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground three screws on the body. Refer to GROUND INSPECTION .
  
  Fig 1: Checking Ground Connections
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 2.
2. NG: Repair or replace ground connections.
CHECK ECT SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect engine coolant temperature (ECT) sensor harness connector.
  
  Fig 2: 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 sensor terminal 1 and ground with CONSULT-II or tester.
  
  Fig 3: Checking Voltage Between ECT Sensor And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  1. Voltage: Approximately 5V
OK or NG
1. OK: GO TO 3.
2. 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 connectors.
3. Disconnect TCM harness connectors.
4. Check harness continuity between ECT sensor terminal 2 and ECM terminal 67, TCM terminal 42. Refer to WIRING DIAGRAM .
  1. Continuity should exist.
5. Also check harness for short to ground or short to power.
OK or NG
1. OK: GO TO 5 .
2. 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
  1. 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
1. OK: GO TO 6.
2. NG: Replace engine coolant temperature sensor.
CHECK INTERMITTENT INCIDENT
Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .
1. INSPECTION END