Stick it to The Man!.. named Allison... which is a girl’s name..?

Discussion in 'Drivetrain & Suspensions' started by Fision, Jun 4, 2018.

  1. Fision

    Fision Registered User

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    I need (ok:rolleyes:, really want) 6th gear unlocked on my tranny and need help.
    I just purchased a 1996 IH 4900 with mechanically injected 250hp dt466 and Allison md3060. So far so good, right? EXCEPT—the Allison has the 6th gear locked out electronically :mad:. Apparently this is a pretty common “thing”; and I can live (with occasional resentment) with a 65mph top speed; but I’d rather not have to redline it in the process. I WANT MY DOUBLE O.D.!! It’s a software issue that requires Allison itself, Allison requires approval from the truck manufacturer (IH, in this case), and IH says “it’s too old, we don’t have records, blah, blah..” Various aftermarket gurus also say it’s too old for them to help with. I think it’s a WTEC II, with a lever shifter (which shows only 5 gears).
    MY ideas: get a TCM (TCU? ECM? ECU? People seem to be using any/all these designations) from another rig that has the same/similar engine&tranny (anybody know of one?); OR get the numbers off such a transmission, bring my TCM into Allison as a “donor” to replace my (supposedly failed) 6 speed TCM, and have them reprogram it to the “OE” 6 speed spec (anybody willing to share some numbers?).
    YOUR ideas?
    Any knowledgeable, experienced help would be MUCH appreciated!
    One last thing: I have only seen my truck in pictures! I live in Alaska, bought it online in the Cleveland Ohio area and will be picking it up Friday June 8 to drive back. 6th gear would sure be nice!
    Side point: anybody know of sources of waste transformer fluid/ATF/oil on the route? I’m looking into setting up a mobile centrifuge/filter to cut down on fuel costs...
     
  2. 79jasper

    79jasper Chickenhawk

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  3. Fision

    Fision Registered User

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    Yup. A royal pain. The thread you posted is the most complete that I’ve run across. Also the longest. From what little I’ve learned about Allison’s (I’ve always owned stick-shifts) my best options are a new compatible TCM with the desired parameters or the numbers off such a tranny that I can take to Allison for reprogramming mine. Anybody out there..? Please:dunno
     
  4. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I have a 99 same truck just a dt466e, I’ll be following this thread closely. 65 mph top speed is brutal
     
  5. Fision

    Fision Registered User

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    The link 79jasper sent has a lot of helpful info. I have an updated form from Allison and the form from IH that I’ll try and post as references for those who would like to try the official route. The feedback I got from IH is that they won’t approve anything older than about ‘04. That’s what they told ME, hopefully others will have a different experience. The rest of us rejects need a back door method.
     
    JAKRANCH likes this.
  6. jwalterus

    jwalterus Made in America

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