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Thread: Messed up

  1. #1
    Jr. Apprentice
    Join Date
    Feb 2011
    Location
    Long Beach Island,NewJersey
    Posts
    12

    Default Messed up

    I hooked my battery up backwards on my 1990 gmc suburban . Now I don't have spark or fuel ECMB fuse was popped and ECMB1 was also ,replaced ECM1 and it stayed ,replaed ECMB and it popped again ,checked one fuseable link by starter ,checked 2 or 3 up top. Nothing! Can anyone help???

  2. #2

    Default

    Welcome to the club. You may have burned up the trucks ECM.

  3. #3
    Legend
    stephan's Avatar
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    Sep 2010
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    Far West, Oregon USA,
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    Welcome to the club Brick. Sorry I've never done that so I can't help you, but someone will be along that can. The closest experience I had was when my mom jumped her car backwards. It burned out the exciter diode in the alternator, but it still started & ran ok, (EFI) it just didn't charge. If your alt light in on when you get it up & running, then just repl the alternator cuz doing the diode is a PITA.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  4. #4

    Default

    You probably toasted the PCM, at the very least. None of the manufacturers put reverse polarity protection on the computers.
    When you hear hoofbeats, look for horses not zebras.

  5. #5
    Legend


    mfleetwood's Avatar
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    Jul 2010
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    Default

    Wow..sorry to hear the news. I hope you are able find out all that was damaged quickly and it doesn't cost you an arm and a leg to fix. Please keep us posted.


    Mike (Denver, CO) - 2008 Sierra 1500 Z71 SLE 5.3L 4WD

    SUSPENSION: Rancho 4" Suspension Lift; Rancho RS9000XL Shocks; Rancho Skid Plates; Rancho MyRide Wireless Shock Controller;
    TIRES:
    BFG All Terrain KO 315/70/17
    DRIVE TRAIN: 4.56 Gears; Detroit TrueTrac Differential; True Cool 40k Transmission Cooler
    PERFORMANCE: DiableSport Predator Tuner; Custom Tuned by Diablew; Magnaflow Exhaust; AFE Cold Air Intake
    ELECTRONICS: Kenwood DNX6180 Touchscreen; Subthump box w/10" Kicker; Driver Information Center (DIC); Rear View Camera
    ACCESSORIES: Westin Brush/Grill Gaurd; Westin Nerf Bars; Truxedo Tonneau; 20% Tint; Tow Mirrors w/Heat & Signals

  6. #6

    Default

    probably best off checking with junk yards and see if you can find a used PCM
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

  7. #7

    Default

    Quote Originally Posted by dualdj1 View Post
    probably best off checking with junk yards and see if you can find a used PCM
    I second that. It doesn't take very much juice at all of the wrong polarity to fry one of those.
    ...
    ....

  8. #8

    Default

    PCMs are pretty cheap at AutoZone. I'll get you a price later.
    When you hear hoofbeats, look for horses not zebras.

  9. #9

    Default

    Cardone Reman should be well under a hundred bucks from AZ.
    When you hear hoofbeats, look for horses not zebras.

  10. #10
    Jr. Apprentice
    Join Date
    Feb 2011
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    Long Beach Island,NewJersey
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    Default

    Hey Thanks for all the info . Still on same situation.still down . Checked everything even changed ECM with the one from my 89 and changed chips to match .same . Have power to coil and power to injectors but no spark and injectors won't fire.things I checked ,coil ,ignition module,fusible links , esc, the only thing left that im not sure about , is it possible for me to have fryd the chips that plug into the computer???any other suggestions or info greatly appreciated

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