Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

What voltage at glow plugs?

Discussion in '1982-Present GM Diesel' started by 86dieselburb, Jan 31, 2005.

  1. 86dieselburb

    86dieselburb 1/2 ton status

    Joined:
    Oct 20, 2004
    Posts:
    219
    Likes Received:
    0
    Location:
    Crestline, CA
    Just out of curiosity I checked the voltage at the glow plugs today and i'm only getting 10.5 volts. Is this enough? Shouldn't it be closer to 12 volts?
     
  2. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    TTT


    This would be good to know, diesel gods...
     
  3. Diesel Dan

    Diesel Dan 1/2 ton status

    Joined:
    Feb 27, 2002
    Posts:
    798
    Likes Received:
    0
    Location:
    Warren, Ohio
    Should be battery voltage. When you get 10.5V is the batteries showing the same? If so your batteries are weak, if they show 12+ volts and only 10.5@ plug then sounds like you are getting voltage drop due to a bad connection.

    Will take a couple of GP cycles to narrow it down. Here is what I'd do. Have someone cycle the GPs while you monitor battery voltage. If it is higher than 10V then check voltage at the battery side of the GP controller, then the GP side of the controller. You could see a drop due to bad contacts in the controller/relay.

    Let us know what you find.
     
  4. 86dieselburb

    86dieselburb 1/2 ton status

    Joined:
    Oct 20, 2004
    Posts:
    219
    Likes Received:
    0
    Location:
    Crestline, CA
    My batteries are both brand new so I would rule them out. Could be a bad connection. Will do some more checking on that end.

    I was lurking around at TheDieselPage and found a post that mentioned what voltage should be at the glow plugs and this was the responce "Voltage at the glow plugs will be 8-9 volts when the glow plug relay is engergized. This is just the normal voltage drop when all 8 glow plugs are drawing over a combined 100 amps."

    So theoretically if I was to disconnect all 8 glow plugs I should get 12 volts if all is working as is supposed to.

    I'll check what Dan mentioned first, and check the voltage at the controller. Since I already know what the glow plug voltage is, this will pretty much narrow it down to the controller or a bad connection.

    Thanks Dan for the idea. I'll post back when I find out more.

    Craig
     

Share This Page