Diagnostic Procedure: Notes

WARNING: This page is about a different car, the 2005 Nissan 350Z. However, it is still accessible from the selected car via links, so may be relevant.

INSPECTION START
Do you have CONSULT-II?

Yes or No
- Yes: GO TO 2.
- No: GO TO 4.
CHECK COOLING FAN LOW SPEED OPERATION
With CONSULT-II
1. Start engine and let it idle.
2. Select "COOLING FAN" in "ACTIVE TEST" mode with CONSULT-II and touch "LOW" on the CONSULT-II screen.
3. Make sure that cooling fans-1 and -2 operate at low speed.
OK or NG
- OK: GO TO 3.
- NG: Check cooling fan low speed control circuit. (Go to "PROCEDURE A ".)
Fig 1: Scan Tool Display "Active Test"
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK COOLING FAN HIGH SPEED OPERATION
With CONSULT-II
1. Touch "HIGH" on the CONSULT-II screen.
2. Make sure that cooling fans-1 and -2 operate at higher speed than low speed.
OK or NG
- OK: GO TO 6.
- NG: Check cooling fan high speed control circuit. (Go to "PROCEDURE B ".)
Fig 2: Scan Tool Display "Active Test Cooling Fan"
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK COOLING FAN LOW SPEED OPERATION
Without CONSULT-II
1. Start engine and let it idle.
2. Turn air conditioner switch ON.
3. Turn blower fan switch ON.
4. Make sure that cooling fans-1 and -2 operate at low speed.
OK or NG
- OK: GO TO 5.
- NG: Check cooling fan low speed control circuit. (Go to "PROCEDURE A ".)
Fig 3: Cooling Fan
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK COOLING FAN HIGH SPEED OPERATION
Without CONSULT-II
1. Turn ignition switch OFF.
2. Turn air conditioner switch and blower fan switch OFF.
3. Disconnect engine coolant temperature sensor harness connector.
4. Connect 150Ω resistor to engine coolant temperature sensor harness connector.
5. Restart engine and make sure that cooling fans-1 and -2 operate at higher speed than low speed.
OK or NG
- OK: GO TO 6.
- NG: Check cooling fan high speed control circuit. (Go to "PROCEDURE B ".)
Fig 4: Connect 150Ω Resistor To Engine Coolant Temperature Sensor Harness Connector
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK COOLING SYSTEM FOR LEAK
Apply pressure to the cooling system with a tester, and check if the pressure drops.
- Testing pressure: 157 kPa (1.6 kg/cm ² , 23 psi)
CAUTION: Higher than the specified pressure may cause radiator damage. Pressure should not drop.

Fig 5: Apply Pressure To The Cooling System With A Tester, & Check If The Pressure Drops
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
- OK: GO TO 7.
- NG: Check the following for leak. Refer to "LEAK CHECK ".
  - Hose
  - Radiator
  - Water pump
CHECK RADIATOR CAP
Apply pressure to cap with a tester.
- Radiator cap relief pressure: 59-93 kPa (0.6 - 1.0 kg/cm ² , 9-14 psi)
OK or NG
- OK: GO TO 8.
- NG: Replace radiator cap.
Fig 6: Applying Pressure Cap With Tester
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK THERMOSTAT
1. Check valve seating condition at normal room temperatures.
  It should seat tightly.
2. Check valve opening temperature and valve lift.
  - Valve opening temperature: 76.5°C (170°F) [standard]
  - Valve lift: More than 8.6 mm/90°C (0.339 in/194°F)
3. Check if valve is closed at 5°C (9°F) below valve opening temperature.
  For details, refer to "WATER INLET AND THERMOSTAT ASSEMBLY ".
  
  Fig 7: Check If Valve Is Closed At 5°C (9°F) Below Valve Opening Temperature
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: GO TO 9.
- NG: Replace thermostat
CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to "COMPONENT INSPECTION ".

OK or NG
- OK: GO TO 10.
- NG: Replace engine coolant temperature sensor.
CHECK MAIN 12 CAUSES
If the cause cannot be isolated, go to "MAIN 12 CAUSES OF OVERHEATING ".
- : INSPECTION END