Gen 1, Auto-Shift, replaced X-Y shifter, now won't shift out of 3rd gear

Discussion in 'Peterbilt Forum' started by Mr. Cob, Feb 12, 2024.

  1. Mr. Cob

    Mr. Cob Light Load Member

    Howdy All,

    I have a 2001 379, I have owned this truck for 6 years in that time I have driven it around 70,000 miles towing my huge RV trailer. In that time I have had NO problems with the transmission. The day we had planned to go south this winter the truck would not start, would not crank at all, the gear indicator showed a dash - rather then a gear number or N for neutral.

    I spent hours on line researching this, had a guy who has the computer program needed come out and check the truck, everything pointed to the X-Y shifter needing to be replaced. Bought a new X-Y shifter, installed it, followed the instructions on how to "calibrate" it. Truck now starts, transmission will go into Neutral, Reverse and Drive. It will move in Reverse, it will move in Drive, but it will NOT upshift or downshift.

    The transmission is programed to start in 3rd gear when it's placed in Drive. When the transmission is working properly, "I" can select any gear from 1st, to 5th as a starting gear. Now when I start the truck and put it into Drive, 3rd gear is selected and engages, but when you drive the truck it will NOT shift, it tires to shift but won't complete the shift when it's in Drive. If I put the shifter in "HOLD" position I should be able to pick a gear to start in AND when moving up shift or down shift at will within the TCM's parameters, this is NOT happening.

    So now I am perplexed as to what could be wrong. Like I said, until the first no start situation this transmission has worked flawlessly, it has always depending on load skip shifted up and down, allowed manual gear selection within parameters, held the gear when in the HOLD position, worked with the Jake and cruise control. Now I don't have a clue what's going on and would appreciate any help or suggestions you folks can offer. Thanks.

    Dave
     
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  3. AModelCat

    AModelCat Road Train Member

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    Speed sensor issue?
     
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  4. Mr. Cob

    Mr. Cob Light Load Member

    Howdy AModelCat,

    I forgot to put this in the first post, I also replaced the two shifter sensors on top of the transmission and the speed sensor on the out put shaft of the transmission.

    Dave
     
  5. DUNE-T

    DUNE-T Road Train Member

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    I have 3 trucks that originally came with auto shifts and ended up converting all to manual. Nobody knows how to work on these trannys anymore and it's a big pain to diagnose.
    The most common problem I had was transmission wiring
     
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  6. Mr. Cob

    Mr. Cob Light Load Member

    Howdy DUNE-T,

    I have read many times that these transmissions can be full converted to manual, but to date NO ONE has posted details on what parts are needed or the actual address of a shop that will do it. Others have said they had it done in chigago, seattle, Dallas and some place in Tennessee, but again no names of shops or part numbers. If you can shed any light on this subject I sure would be interested. Thanks.

    Dave
     
  7. JB7

    JB7 Medium Load Member

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    Go on the Eaton website. There are complete troubleshooting manuals, how to get codes without the software. Just have to know how to read and follow simple instructions and use a multimeter. Manuals are free to download. Can't post here because the files are too large, tried it before, some are almost 400 pages. I would closely check all the wiring at the trans, pull apart the connectors and look for corrosion. Might be a module issue. You can also call Eaton for help with diagnosis.
    The Autoshift have the same guts as the manual trans. Just that the autoshift is controlled by computers.
     
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  8. DUNE-T

    DUNE-T Road Train Member

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    I can give you info on shops in Detroit and Chicago, who can do it. Pm if you need.
    You basically need a new transmission top plate ($500) and a meritor electrical 10 speed stick ($200 at a junk yard). The rest is labor, dropping the transmission, making a new harness, reprogramming the ecm (depending on the engine). Might as well throw in a new clutch.
    I did my last one like 3-4 years ago and all together it was under $3k. Might be a bit more expensive now, since price of labor went up.
    There is also a possibility that your tranny itself needs a repair. I suggest to not waste time and just get a rebuilt exchange for like $3500 instead of tearing old one apart. I bought mine from Valley Truck Parts in MI
     
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  9. lester

    lester Midwest's #1 Feed Hauler

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    what transmission do you have? I also had a 2001 pete with an 18 speed autoshit. I converted it and was much happier.
    parts needed.
    New transmission case, couple sliders and maybe 1 gear. used top plate and shift tower, simple parameter change in ecm and probably disable a neutral safety switch( I didn't know that and just ran a new wire to starter)
    inland truck parts did my conversion. he just looked at the parts list for the auto vs manual and changed anything that was different.
    I can give you more details if you have the same transmission and are interested
     
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  10. Mr. Cob

    Mr. Cob Light Load Member

    Howdy Lester,

    I have the 18 speed A-S transmission and C-15 engine. I have heard that the case is different and that a regular shifter plate will NOT bolt to the Auto-Shift case but some have mentioned an adapter plate but again no details. If you have the time please provide me with as much detail as you can. THANKS.

    Dave
     
  11. lester

    lester Midwest's #1 Feed Hauler

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    yup same exact setup I had. the difference in the case and the reason you have to buy I different one is a single missing hole. the A/S case doesn't have a hole for the lockout pin for the range shift(something like that anyway, my terminology may be off. but basically it's what keeps the transmission from trying to shift range while in gear and destroying itself.
    most autoshits came with a solo, self adjusting clutch, they are garbage. if it still has one, get rid of it!
    I did this probably 10 years ago. cost me 2-3k then. for me it was Well worth the cost. I removed and replaced transmission and had a shop do the actual transmission work.

    Inland truck parts. sioux city, IA. ask for Doug. he knows his stuff.
    but like I said before a simple comparison of part numbers is really all anyone needs.
    reused most all my original gears and bearings.
     
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