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  1. #1

    Default Allison tranny problems

    I have a 2001 Silverado 2500 HD with the allison 5 speed. Today after running fine it just seemed to go belly up. It does not show what gear I'm in on the dash gear indicator and will not shift into gear properly. If I shift to first and then start shifting up manually it seems to work. Could this be the neut safety/ backup switch or a fliud problem 58k on the odo.

  2. #2

    Default

    It sounds electrical to me. Were you casual driving, or something different?

    I don't have much experience with Little Alli, but with the dash out and no auto shift, it sounds like something came unplugged. I'd crawl underneath and look for loose plugs. Check for codes, too.

    Good luck,

    1999 Chevy K2500 Suburban 350
    K&N, reworked cai, Thrush cat-backs
    Vinyl, cranks, floor shift, and rear air!

  3. #3

    Default

    Quote Originally Posted by sr71 View Post
    I have a 2001 Silverado 2500 HD with the allison 5 speed. Today after running fine it just seemed to go belly up. It does not show what gear I'm in on the dash gear indicator and will not shift into gear properly. If I shift to first and then start shifting up manually it seems to work. Could this be the neut safety/ backup switch or a fliud problem 58k on the odo.
    This is a very common problem on the Allison 1000. The NBSU switch goes bad. NBSU is the neutral safety switch. There's plenty of info on how to change it on the net. Just Google NBSU.
    Jim

    2004 SILVERADO 2500HD LS
    Pro Comp Leveling Kit
    285-75-16 Cooper ST All Terrains
    Pro Comp Programmer
    Bilstein Shocks
    Linux Bed Liner
    Tinted Windows



    Other rides:

    1967 Landcruiser <350 Chevy>
    1970 Camaro
    1990 Geo Metro Convertible
    2007 FJ Cruiser

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