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  1. #1
    Sr. Apprentice
    Join Date
    May 2009
    Location
    Massachusetts
    Posts
    48

    Default Calling all experts Ignition/Wiring Problems (Copied from Suburban forums)

    So I started around 9am after the guy that is helping me put in my new rebuilt tranny in my 1998 Chevy Suburban.

    After he finished putting the tranny in went and connected the battery back up and the truck wont start just sits and cranks all day. So I checked the usual things no loose connections, no plugs -- unpliugged, and today I spent all day basically just throwing parts at it:

    Brand New Battery
    New Ignition Coil
    New Ignition Control Module
    New Distributor (suspected faulty camshaft position sensor
    New Accel Rotor & Accel Cap
    NewCrankshaft Position Sensor
    Re-timed it cause thought it might had been messing with the camshaft sensor

    And now anytime the aux wire that runs from the battery to the fuse box is in circuit with the battery it is blowing the ECM-B (20amp) fuse underneath the hood in the fuse box, would that be a clear cut sign of a bad computer or just a short somewhere?

    Tested the Ignition Coil/Module for 12V and it was indeed there, 12v all the way to the distributor cap, is the computer junk and not sending the signal to send spark or is there something else I am missing?

    Going to the salvage yard tomorrow to pick up a new PCM/Engine Computer for the next step...

    Am I heading in the right direction with all these swaps, or is it something simple as a crossed wire somewhere.

    I spent about 12 hours today and just started throwing parts at it with no results hoping I explained enough so someone can come up with something cause I'm stumped about now...

    Thanks,

    -Jon D.

  2. #2

    Default

    check to see if your even getting spark to the plug wires you can buy a spark plug that has a clip on it and put that in the #1 spark plug wire and clamp that to ground the have some one crank it its not uncommon for a new cap to be bad they tend to arch internally and only put spark out to the #3 also check to see if your getting voltage from your throttle position sensor you should have low voltage at first then slowly open the throttle body at wide open you should have no more then 5 volts ignition on of course and the aux wire is proaby corroded up by the battery also check to see if you have good grounds at the battery and starter area

  3. #3

    Default

    I doubt very seriously that you have a bad PCM. Unplug the connector to the transmission and see if your problem goes away. If it does than there's a short inside the transmission. If not what could have happened is a wire got pinched in your bell housing between the engine block. Get a flashlight and a small mirror and you will see it.
    Jim

    2004 SILVERADO 2500HD LS
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  4. #4
    Sr. Mechanic John W's Avatar
    Join Date
    Sep 2007
    Location
    St Peters, Nova Scotia, Canada
    Posts
    158

    Default

    If you had the tranny out check that there are no wires caught between it and the engine block. That could cause the short blowing the fuse and the no start problem.
    2000 4x4 Ext. cab 5.3 Z71
    2009 Corolla

  5. #5
    Master Mechanic daddytech's Avatar
    Join Date
    Mar 2008
    Location
    Portland TN
    Posts
    672

    Default

    I agree with the two previous posts also the no start deal could be caused by the wires to the transmission either not being hooked up or plugged in correctly. might want to back track and make sure that everything is plugged back in on the transmission and ensure there are no empty plugins or loose hanging plugs anywhere up under there too. If the transmission isn't giving the signal the truck is in park or neutral then that would cause a no start situation but it shouldn't be turning over either if that were the case so i am kinda leaning toward something being pinched between the transmission bell housing and the engine block. I am like the others too in that I don't think that anything should be poping those fuses. you might go rent the code reader and see if there are any codes being thrown by the computer too.

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