Diagnostic Procedure

CHECK ECT SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch "OFF".
2. Disconnect engine coolant temperature (ECT) sensor connector.
  
  Fig 1: Disconnecting Engine Coolant Temperature (ECT) Sensor Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Turn ignition switch "ON".
4. Check voltage between ECT sensor connector terminal 1 and ground with CONSULT-II or tester.
  
  Fig 2: Checking Voltage Between ECT Sensor Connector Terminal 1 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Voltage: Approximately 5V
OK or NG
1. OK GO TO 3 .
2. NG GO TO 2.
DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors F112, F28
- Harness for open or short between ECM and engine coolant temperature sensor
  1. Repair harness or connectors.
CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND CIRCUIT
1. Turn ignition switch "OFF".
2. Disconnect ECM harness connector.
3. Check harness continuity between ECT sensor terminal 2 and ECM terminal 67.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
4. 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 following.
- Harness connectors F112, F28
- Joint connector F204
- Harness for open between ECM and engine coolant temperature sensor
- Harness for open between TCM and engine coolant temperature sensor
  1. Repair open circuit or short to power in harness or connectors.
CHECK ENGINE COOLANT TEMPERATURE SENSOR
Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.

Fig 3: Checking Resistance Between Engine Coolant Temperature Sensor Terminals 1 And 2
Courtesy of NISSAN MOTOR CO., U.S.A.

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