Diagnostic Procedure

CHECK POWER SUPPLY
1. Turn ignition switch OFF.
2. Disconnect engine coolant temperature sensor harness connector.
3. Turn ignition switch ON.
  
  Fig 1: Disconnecting Engine Coolant Temperature Sensor Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
4. Check voltage between engine coolant temperature sensor terminal 1 and ground with CONSULT-II or tester.
  Voltage : Approximately 5V
OK or NG
1. OK : GO TO 3.
2. NG : GO TO 2.
  
  Fig 2: Checking Voltage Between Engine Coolant Temperature Sensor Terminal And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
DETECT MALFUNCTIONING PART
Check the harness for open or short between ECM and engine coolant temperature sensor.
1. : Repair harness or connectors.
CHECK GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check harness continuity between engine coolant temperature sensor terminal 2 and engine ground.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
3. Also check harness for short to power.
OK or NG
1. OK : GO TO 5.
2. NG : GO TO 4.
DETECT MALFUNCTIONING PART
Check the harness for open or short between ECM and engine coolant temperature sensor.
1. : Repair open circuit 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 THERMOSTAT OPERATION
When the engine is cooled [lower than 76.5° C (170° F)], condition grasp lower radiator hose and confirm the engine coolant does not flow.

OK or NG
1. OK : GO TO 7.
2. NG : Repair or replace thermostat. Refer to THERMOSTAT .
CHECK INTERMITTENT INCIDENT
Perform TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .
1. : INSPECTION END.