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Glow plugs not getting hot enough

Discussion in '1982-Present GM Diesel' started by icemanoh58d, Mar 15, 2006.

  1. icemanoh58d

    icemanoh58d Registered Member

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    Not really sure what's going on now... the glow plug relay is cycling but the sound is much weaker than normal and the light isn't coming on in the truck tried to use a jumper wire this morning but didn't work either. just cycled very weak checked all the connections looked good but was wondering if it has something to do with the glow plugs themselves being bad. Also when I correct this problem I am going to a manual setup thanks to the diesel guru's should be no problem however , how much of the other portions of that system can I get rid of I was planning on running all new wires to the glow plugs themselves as mine are good but of poor quality I wanted to run a bit heavier guage wire to them and didn't know if there was some way to bypass the glow plug control unit completely when doing this again thanks for any help you guys have saved me alot of time and money since I joined up

    Trev
     
  2. darkshadow

    darkshadow 1 ton status

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    how old are the plugs?

    they stop working and i would asume get weeker befor that also.

    maybe try pulling one and see what shape it is in.
     
  3. icemanoh58d

    icemanoh58d Registered Member

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    I'm gonna take a look at them this weekend was just wondering if this was a common side effect of bad GP's they didn't really get weak gradually it just kinda happened one day. As far as the age of the plugs it is about three years and that's including the year the truck sat while I was away

    Trev
     
  4. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i'm not sure that the symptoms you describe would suggest bad glow plugs. no reason you couldn't take a few out and check them tho - it's easy stuff. i just don't see why a bad plug would make the GP controller weak.
     
  5. icemanoh58d

    icemanoh58d Registered Member

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    not sure myself especially since it's a brand new relay only three months old

    Trev
     
  6. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    maybe there's some kind of issue between the ignition switch and the relay. the swap to a manual is easy - as you probably know. you might just try that and see if that fixes the problem.
     
  7. icemanoh58d

    icemanoh58d Registered Member

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    thought about that but when I used a jumper wire to heat up the gp's it still didn't work

    Trev
     
  8. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    oh, i see, i misunderstood. i thought you were just trying to jump your truck, not running other batteries directly to the gp relay.
     
  9. maynardogle

    maynardogle 1/2 ton status

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    Sounds to me like one of your batteries has gone away....and is maybe pulling down the other one. Have you checked voltages at the battery terminals, or at one of the big terminals on the glow plug relay when plugs are cycling? You should have 12.4 or so when the ignition key is off, 10.9-11 whan glow plugs cycle and 12.1 or 12.2 between cycles. If any of these numbers are low, separate the batteries, charge em up and make sure they both float (fully charged, no load) at 12.4 or so.
     
  10. icemanoh58d

    icemanoh58d Registered Member

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    I'll give that a shot as well got two brand new red tops and deep cycle charged them before using them but you never know apparently sometimes they're just bad or go bad really quick from what I've been told. Or is that just urban legend and the truth is usually that something else is causing the truck to use up batteries red top or not.

    Trev
     
  11. imiceman44

    imiceman44 1 ton status

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    Well urban legend or not I don't know, I know when mine failed I blamed the red tops then found out I had a short that killed them.
    First one took 3 cycles to die the other held on for 3 more cycles then died, it did die after I found the short so now I have a good new set and it's fine.
     

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