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ECT sensor

Discussion in 'GM 6.5 Diesel Engines' started by chrisk1500, May 9, 2008.

  1. chrisk1500

    chrisk1500 New Member

    May 5, 2008
    The ECT (engine coolant temperature) sensor is located in the coolant crossover tube. It has a weatherpack connector running to it with two wires (yellow and black).

    The truck's computer uses the information from the ECT to adjust a number of things. It determines timing advance, OD engagement, fuel delivery, and glow time. Unplugging the ECT is a diagnostic aid used to check the glow system. This is because when the ECT sensor is unplugged the computer thinks the engine is -40* F.

    Here is a table of resistance values and temperatures you can use to check your ECT.

    177 ohms @ 212 deg. F. or 100 deg. C.
    241 ohms @ 194 deg. F. or 90 deg. C.
    332 ohms @ 176 deg. F. or 80 deg. C.
    467 ohms @ 158 deg. F. or 70 deg. C.
    667 ohms @ 140 deg. F. or 60 deg. C.
    973 ohms @ 122 deg. F. or 50 deg. C.
    1188 ohms @ 113 deg. F. or45 deg. C.
    1459 ohms @ 104 deg. F. or 40 deg. C.
    1802 ohms @ 95 deg. F. or 35 deg. C.
    2238 ohms @ 86 deg. F. or 30 deg. C.
    2796 ohms @ 77 deg. F. or 25 deg. C.
    3520 ohms @ 68 deg. F. or 20 deg. C.
    4450 ohms @ 59 deg. F. or 15 deg. C.
    5670 ohms @ 50 deg. F. or 10 deg. C.
    7280 ohms @ 41 deg. F. or 5 deg. C.
    9420 ohms @ 32 deg. F. or 0 deg. C.
    12300 ohms @ 23 deg. F. or -5 deg. C.
    16180 ohms @ 14 deg. F. or -10 deg. C.
    21450 ohms @ 5 deg. F. or -15 deg. C.
    28680 ohms @ -4 deg. F. or -20 deg. C.
    52700 ohms @ -22 deg. F. or -30 deg. C.
    100700 ohms @ -40 deg. F. or - 40 deg. C
  2. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    Hey I'm thinking once we get it all together a new & better Phoenix will arise from ashes.

    Looks good Chris
  3. RadioMan

    RadioMan Recruit

    May 9, 2008
    SW Tennessee
    Thanks! Just printed the values for tomorrow.
    My ECT is not only disconnected, but the plug has been cut off :wtf:

    The bucket truck has remote start and stop from the bucket. I wonder if the remote start is the reason ECT being disconnected :confused5:
    The lift pump also runs all the time, I don't think that this is a good thing. Probably also for the remote start to work (?). I haven't found how the LP is being kept running yet - could be the OPS is stuck -- or it was done intentionally.

    Seems to me that once the engine cranks a bit the OPS will turn the LP on anyway, so it doesn't need to be on all the time. Correct??
  4. preachermic

    preachermic New Member

    May 31, 2008
    Bostic, NC
    Thanks Chris I will check it tomorrow morning. My ECS sensor is about 2 years old and my truck starts very rough unless I set the switch to where the ECS sensor is bypassed . Other than that my truck runs perfect.
  5. preachermic

    preachermic New Member

    May 31, 2008
    Bostic, NC
    I'm getting 3.1 ohms. I'm guessing that the sensor is dead.
  6. JiFaire

    JiFaire Lieutenant Staff Member Lead Moderator

    Feb 10, 2008
    Alberta, Canada
    Yep - that's pretty much a dead short. Your glow plugs will be at the minimum cycle, so you may have some cold-start issues as a result.

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