How does the glowplug temperature sensor work? - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• How does the glowplug temperature sensor work? by srivett on 19 Jan, 2005 16:37
• Hi all,
    I've been having difficulties with my glow plug light in the dash.  It will not go out before starting the car.  While doing some trouble shooting I found that the contacts between the two prongs of this sensor have an infinite resistance.  Well, my replacement is the same way.  So, how does this sensor work?  Is it an off-on sensor?  My temperature guage sensor is a variable resistance and does not read infinite.
  
  Thanks, Steve
• #1 by jtanguay on 19 Jan, 2005 17:02
• well then it probably opens at either a certain temperature, or a certain amount of current draw.  Sorta like the transistor in your computer maybe...  I could be wrong though!  If the light fails in the dash, have you checked the fuse?
• #2 by srivett on 19 Jan, 2005 17:16
• The light works but it isn't giving me the correct waiting time.  It stays on until I start the car.  This may be a problem with the glow relay but I'm still curious as to how the sensor works as I may return the new one.
  
  Steve
• #3 by MacGyver on 19 Jan, 2005 17:32
• So by stating the light stays on till you start the car, you mean ten seconds or five minutes regardless? I mean literally, 5 minutes? What's the longest you've waited?
  Have you verified the GP's actually receive power continuously till you start the car, also regardless of the length of wait time? Or is it just the light out of wack?
  Sorry, I don't have the manual in front of me to see if it gives check for sensor verification.
• #4 by fatmobile on 20 Jan, 2005 01:03
• Quote

  I found that the contacts between the two prongs of this sensor have an infinite resistance

  
   Your sensor has 2 prongs?
   Your problem sounds like what happens to me when I disconnect the sensor wire, from the sensor.
• #5 by srivett on 20 Jan, 2005 01:31
• Ugh, that was a bad piece of English on my part.  The reading I get is infinte when I measure the resistance between the two prongs.  FWIW my parts guy did dig up a 4 prong sensor which must be a two in one.
  
  Anyway, I finally found something in my Bentley too.  It says there should be infinite resistance above 50C and grounded below 50.  Unfortunately the wiring diagram differs between a couple sections of the manual so it doesn't make a lot of sense.  Is there another temperature guage inside the relay?
  
  Steve