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Thread: 1227747 problems

  1. #1
    Carb and Points!
    Join Date
    Feb 2012
    Posts
    6

    1227747 problems

    Hi

    I am having trouble with my 89 Suburban 5.7L TBI.
    I can not get a code 12 ( or any other code ) from the system.

    Original ECU blew the ECU-B fuse instantly.
    Replaced ECU and got a solid CES light on ignition on.

    I have followed chart A-2 all the way down the left side.
    I get 5v out of Diagnostic pin (pin B) on ALDL connector.

    When I ground Pin B, either to Bin A or another ground point
    I get a quick CES light, a short no light, then a solid CES light.

    I have replaced ECU with another (3rd) unit with no change in behavior.
    It seems unlikely that both replacements... junk yard pulls ... would exhibit same error.

    What Now????
    Do I need to probe some of the connectors right at the ECU?
    Maybe Diagnostic to Ground?

    Should I try reading serial Diagnostics from pin E ?
    I have not tried as I am assuming that if the check engine light diagnostic is not working then the
    serial ALDL data will also be at fault.

    Bob

  2. #2
    Fuel Injected!
    Join Date
    Jan 2016
    Posts
    32
    Sounds like you need to make sure the PROM is seated properly in the socked.

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