Volkswagen Cars 2000-05

Glow Plugs

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Diagnosis & Testing



  1. Disconnect the engine temperature sensor.
  2.  
  3. Connect a test light between No. 4 cylinder glow plug and ground. The glow plugs are connected by a flat, coated busbar, located near the bottom of the cylinder head.
  4.  
  5. Turn the ignition key ON ; the test light should light, then go out after 8-30 seconds.
  6.  
  7. If there is no voltage, go to Step 7.
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  9. To test each plug individually, disconnect the wire and remove the busbar from the glow plugs.
  10.  
  11. Connect an ohmmeter to each glow plug connection or use a test light. Each plug must have continuity to ground. The engine will probably start with one defective glow plug, but it will make a lot of smoke.
  12.  
  13. To test the glow plug control system, remove the glow plug relay from the bottom right socket of the main fuse/relay panel.
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  15. With the ignition switch OFF , there should be 12 volts at terminal 30 on the socket in the panel. Terminal 85 should have continuity to ground.
  16.  
  17. Disconnect the stop solenoid wire from the pump so the engine will not start. With the ignition switch ON , there should be 12 volts at terminal 86. When the starter is operated with the ignition switch, there should be 12 volts at terminal 50.
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  19. Install the relay and disconnect and ground the temperature sensor wire. Connect a voltmeter or test light to the glow plug busbar.
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  21. With the stop solenoid wire still disconnected, operate the starter with the ignition switch. There should be power to the glow plugs.
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  23. If all voltages at the socket are correct but there is not power to the glow plugs, the relay is faulty and must be replaced.
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Removal & Installation



  1. Remove the busbar connecting the glow plugs and determine which plugs need replacement.
  2.  
  3. Remove the defective plugs.
  4.  
  5. When installing new plugs, tighten to 22 ft. lbs. (30 Nm).
  6.  


NOTE
Diesel glow plugs have an air gap much like a spark plug to prevent overheating of the plug. Over-torquing the glow plug will close the gap and cause the plug to burn out.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove the bus bar connecting the glow plugs and determine which plugs need replacement.
  4.  
  5. Remove the defective plugs.
  6.  
  7. When installing new plugs, tighten them to 11 ft. lbs. (15 Nm).
  8.  


NOTE
Diesel glow plugs have an air gap much like a spark plug to prevent overheating of the plug. Over-tightening the glow plug will close the gap and cause the plug to burn out.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the bus bar connecting the glow plugs and determine which plugs need replacement.
  4.  
  5. Remove the defective plugs.
  6.  
  7. When installing new plugs, tighten them to 11 ft. lbs. (15 Nm).
    NOTE
    Diesel glow plugs have an air gap much like a spark plug to prevent overheating of the plug. Over-tightening the glow plug will close the gap and cause the plug to burn out.

  8.  

 
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