Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Glow Plug System

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GENERAL DESCRIPTION



See Figures 1, 2, 3, 4, 5, 6 and 7

The auto glow system provides the pre-glow (fast glow) operation before the engine starts, as well as after-glow operation after the engine has started. The system consists of a water temperature sensor, glow plug relays, dropping resistor and glow control unit.

The system incorporates a glow plug light on the instrument cluster. The length of time that the light is on is controlled by the temperature of the engine.

Pre-glow

The pre-glow system operates for about 6 seconds when the engine temperature is below 122°F (50°C). After the engine starts, the pre-glow system turns OFF.

After-glow

The after-glow system operates for a specified length of time after the ignition switch is turned from OFF or ST to ON , when the engine temperature is below 122°F (50°C). The length of time varies from 5 to 32 seconds. After pre-glow, the after-glow system turns OFF when the terminal voltage of the glow plug is higher than 7 volts. When the ignition switch is in the ST position, the after-glow system is energized.





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Fig. Fig. 1: Glow plug relay terminal identification

 


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Fig. Fig. 2: Glow plug system component locations

 


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Fig. Fig. 3: Glow plug system wiring diagram-1982-85 vehicles

 


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Fig. Fig. 4: Glow plug system wiring diagram-1986-87 vehicles

 


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Fig. Fig. 5: Glow plug system diagnostic chart (part 1 of 2)

 


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Fig. Fig. 6: Glow plug system diagnostic chart (part 2 of 2)

 


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Fig. Fig. 7: Diesel engine diagnostic table

 

Glow Control Unit Terminals

See Figure 8



Terminal 1-Measured voltage to the glow plug
 
Terminal 2-Control unit power source
 
Terminal 3-Control unit ground source
 
Terminal 4-ON/OFF operation of glow relay 1
 
Terminal 5-Water temperature sensor power terminal
 
Terminal 6-Ignition switch START position
 
Terminal 7-ON/OFF operation of glow relay 2
 
Terminal 8-Water temperature sensor ground terminal
 
Terminal 9-Glow light power source
 
Terminal 10-Used to determine engine has started
 

TESTING



Water Temperature Sensor
  1. Remove the sensor from the engine and place in a pan of water.
  2.  
  3. Measure the resistance with an ohmmeter at varying temperatures.
  4.  
  5. Compare the readings to the following values:

    50°F (10°C)-3.7-
     
    68°F (20°C)-2.5-
     
    122°F (50°C)-0.85-
     
    176°F (80°C)-0.33-
     

  6.  
  7. Replace the sensor if found defective.
  8.  

Glow Plug

Remove the glow plug from the engine. Using an ohmmeter, check that there is continuity in the plug. If not, replace the glow plug and torque to 25 ft. lbs. (34 Nm).

Dropping Resistor

See Figure 9

Disconnect the resistor and measure the resistance between the 2 terminals. The resistance should be about 0.1-. If not, replace the dropping resistor.





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Fig. Fig. 8: Glow control unit terminal identification

 


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Fig. Fig. 9: Dropping resistor testing

 

 
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