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.
  
  Fig 2: Checking ECT Sensor Power Supply Circuit
  Courtesy of NISSAN MOTOR CO., U.S.A.
2. Turn ignition switch ON.
3. Check voltage between ECT sensor terminal 1 and ground with CONSULT-II or tester.
  - Voltage: Approximately 5 V
OK or NG
- OK: GO TO 4.
- NG: GO TO 3.
Fig 3: Checking Voltage Between ECT Sensor Terminal & Ground
Courtesy of NISSAN MOTOR CO., U.S.A.
DETECT MALFUNCTIONING CHART
Check the following.
- Harness connector F26, F101
- Harness for open or short between ECM and engine coolant temperature sensor
  - 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. 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 ground or short to power.
OK or NG
- OK: GO TO 6.
- NG: GO TO 5.
DETECT MALFUNCTIONING PART
Check the following.
- Harness connector F26, F101
- Harness for open and short between ECT sensor and ECM
  - 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 7.
- NG: Replace engine coolant temperature sensor.
CHECK INTERMITTENT INCIDENT
Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .
- : INSPECTION END