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TBi trouble

Discussion in 'The Garage' started by jamber2541, Oct 9, 2006.

  1. jamber2541

    jamber2541 1/2 ton status

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    Can someone translate this to English


    The EST signal did not change when the ECM applied bypass voltage to the ignition module
     
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Something up with your ignition system...

    Couple possiblities that come to mind:

    First is your knock sensor. Basically, when you first start the truck, it advances the timing enough to cause the engine to start pinging, then waits for the approriate voltage signal from the knock sensor. If it doesn't get it, it switches to a fixed timing table, and sets an error code. Check to see if you've got any resistance in your knock sensor, if its an open connection, something is wrong. You won't get a continuity test to work, need to actually check the ohms. I think TBI sensors are suppost to be either 100k ohms, or 3.8k ohms...

    Second is a bad ignition module. Try taking it to your local parts house, many of them can test them for you.

    Third is a bad EST module. Its the big flat module just to the pass side of your throttle body. I've never personally had one go bad, but I imagine is a possiblity.
     
  3. btolenti

    btolenti 1/2 ton status

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    would that be a code 42?
     
  4. jamber2541

    jamber2541 1/2 ton status

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    that is it, code 42
     
  5. btolenti

    btolenti 1/2 ton status

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    Check the things sierra classic said....could also be a bad pickup coil in the distributor.

    Also check your grounds. Recently, I have seen a few problems caused by bad grounds....
     

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