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distal703's avatar
distal703
Explorer
Nov 01, 2019

Allison 2500 downshift issue

I have a 2014 Itasca Meridian 34B with a 2500 Allison 6-speed trans. Lately when I am in cruise control it does not downshift as needed. Especially from 6 to 5. When in 5th it downshifts when needed part of the time. Some times when I first start out in the morning it shifts fine, but when I stop for a break it stops downshifting properly. It works fine in non-cruise control mode. I'm thinking it's a sensor, but which one and is it a DIY item?
Class A
  • SidecarFlip's avatar
    SidecarFlip
    Explorer III
    Nov 01, 2019
    Basically nothing on an Allison is DIY except fluid and filter changes and even that requires specific fluid and filters. Take it to an Allison repair facility and let them diagnose the exact issue and repair it accordingly. Allison.s are very touchy about fluid change intervals too. Are you doing that?
  • wolfe10's avatar
    wolfe10
    Explorer
    Nov 02, 2019
    Not familiar with the 2500.

    But, on all their larger transmissions you can check for DIAGNOSTIC CODES from this shift pad.

    See if this feature is available for your 2500.
  • jplante4's avatar
    jplante4
    Explorer II
    Nov 02, 2019
    Does the 2500 have a mode button? On the 3000, if that is pressed it delays the downshift (kind of like Eco mode) to prevent constant downshifting on gentle hills. The display should say Mode On or something like that. It's possible that the ECM has been programmed to turn that on with the cruise control.

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