98 Tahoe ECM-1 fuse blowing

Discussion in 'Engine & Drivetrain' started by m2q, Feb 20, 2011.

  1. m2q

    m2q TYF Newbie

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    Mike
    Here's what I did:
    • with FI assy, ECM disconnect and fuse out: checked each FI pink feed back to the ECM-1 fuse to check continuity; checked ea FI colored wire back to ECM to confirm continuty
    • with FI assy disconnected, checked resistance across each injector's connectors; res registered 11-9 to 12.1
    • with FI assy connected and ECM-1 fuse in, fuse blows when power is turned on whether if ECM is connected or not

      I'll try what you suggest on the wire voltage check and additional injector checks and let you know what I find
     
  2. m2q

    m2q TYF Newbie

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    With ECM fuse in-place, ECM connected and power on, checked voltage from each FI pink supply wire; with multimeter to ground, voltage measured 12.11v for each wire; with multimeter connect to pink wires and corresponding wire to ECM, essentially across FI connection, voltage measured 11.93v.

    Power output at ECM fuse to ground was 12.12v.

    With fuse removed, FI body and ECm disconnected, resistance from FI connector to ECM connect was about 4 ohms for each wire; continuity verified.

    resistance across fuel injector connection pins was 12.1 ohms for 6 injectors and 11.9 ohms for 2.

    ECM fuse still pops when ECM and FI body are connected and the power is turned on; disconnect the FI body and all is well.
     
  3. SunlitComet

    SunlitComet OBS Jedi-Do Good

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    Then yes the injection body would seem to be at fault. Just can't see that with all the injector almost the same readings although they may be breaking down electrically when there is power on the unit. The only other farscape idea I can think is the pcm drivers are kepping all the injector open at one but that is still not enough current to blow the fuse.
     
  4. m2q

    m2q TYF Newbie

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    The FI body was my conclusion as well. Thanks very much for your time and assistance.
     
  5. Spikesdaddy

    Spikesdaddy TYF Newbie

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    I'm having what seems to be the same issue with my 1999 GMC YUKON ( L31, 5.7). I unplug the main plug to the fuel injectors (on top of the manifold), replace the fuse and it doesn't blow the fuse. Plug the harness back in and it instantly blows the PCM-1 (20 amp) fuse. Mine was replaced 4 years ago by a dealer in Georgia with part number 19210687. I'm thinking I have a bad injector or a short at one or more injectors? Does it sound like I'm correct?
     
  6. Spikesdaddy

    Spikesdaddy TYF Newbie

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    I'm having what seems to be the same issue with my 1999 GMC Yukon ( L31, 5.7). I unplug the main plug to the fuel injectors (on top of the manifold), replace the fuse and it doesn't blow the fuse. Plug the harness back in and it instantly blows the PCM-1 (20 amp) fuse. Mine was replaced 4 years ago by a dealer in Georgia with part number 19210687. I'm thinking I have a bad injector or a short at one or more injectors? Does it sound like I'm correct?
     
    Last edited by a moderator: Aug 9, 2018

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