Allison Transmission Questions

Discussion in 'General RVing' started by AllisonMan, Apr 5, 2003.

  1. Allison Expert

    Allison Expert New Member

    Re: Allison Transmission Questions

    It could just need to be re-adjusted. After time the cable will stretch and the linkage can wair, and/or the modulator itself could be going bad.
     
  2. cummin8.3

    cummin8.3 New Member

    Re: Allison Transmission Questions

    Makes Sense! I have a couple diesel leaks I need to repair and I will test drive again and see how it shifts. I also should change the transmission fluid. I had it serviced about 4 years ago. Only drove about 1000 miles since then. It is clean and smells good, I guess that's a good thing. I'm going to change it myself this time.

    Thanks...
     
  3. Phil L

    Phil L New Member

    RE: Allison Transmission Questions

    I have a 2006 freightliner motorhome with an Allison MH3000 series transmission. The transmission does not start downshifting when the exaust brake kicks in as it should. The local allison dealer says the transmission is not seeing an input from the service brake switch to tell the Allison that the brakes are being applied. They say that is a freightliner wiring problem. Can anyone tell me what connector and what pin the brake switch hooks to on the allison WETC III controller?
     
  4. Allison Expert

    Allison Expert New Member

    Re: Allison Transmission Questions

    The transmission computer is programmed to pre-select a range when the exhaust brake is activated. It is possible that the vehicle side truly is not sending the signal as it should be, which could be caused by a broken wire, chaffed wire, or bad connection somewhere in the vehicle harness. Freightliner does not use a VIM (vehicle interface module) like most OEM's. The brake switch and all of the accessories are wired in/out of the Gray connector which is all of your GPI/GPO (General Purpose Input/General Purpose Output). You would need to get a wiring schematic from a Freightliner dealer to see how their wiring is run and what the wire numbers are. At the back of the brake switch, see what color the wires are and the wire numbers and let me know, and maybe I can point you in the right direction from there.
     
  5. mgthomas

    mgthomas New Member

    Re: Allison Transmission Questions

    allison expert i have a md3060 in 94 spartan, speedo quit about a year ago but cruise and tach still worked so drove it. last trip out cruise worked about 30 miles then dropped out never to come on again, on a 3200 mile trip the speedo added all most 4 miles never saw the needle move. it has never added miles before since speedo quit. where is the speedo plug on the md3060 i found a 2 wire plug behind the output shaft it was clean and a large plug bolted to transmission plug didn't unplug it but outside looks ok. spartan taps the same speedo pulse wire that the speedo uses to feed the cruise. any help greatly appreciated!
     
  6. Allison Expert

    Allison Expert New Member

    Re: Allison Transmission Questions

    First thing, have you ever gotten a check trans light or a check engine light or gotten any kind of trouble codes from the trans via the shift pad? Some OEM's will use a speed sensor located at the rear diff. that also communicates with the transmission speed sensors and computer. You could possibly just have a bad or loose wire somewhere in the dash for the tachometer/speedometer and/or cruise control.
     
  7. velocette

    velocette New Member

    Re: Allison Transmission Questions

    ATTENTION ALLISON Expert. I have an old Monaco 1991 with an Allison 643, 275 Cummins 8.3. I am overheating the transmission in 1st & 2nd gear when pulling steeper hills. 3rd & 4th are no problem and it will pull fine with my Grand Cherokee on the back.
    Changed fluid and filter twice, flushed cooler and increased fan speed but it still gets hot 220 in 1st and 2nd. barely moves off 190 when pulling a hill in 3rd gear.
    Is this transmission adjustable? or does it need a rebuild? or replacement?
     
  8. velocette

    velocette New Member

    Re: Allison Transmission Questions

    i have a Monaco with and Allison 643 and its started overheating when pulling hills, but only in 1st & 2nd gear. No problem pulling hills in 3rd or 4th temp guage barely moves of 190 same as engine guage.
    have flushed fuid twice and changed filter twice in the last 3,000 miles to no avail. Flushed trans cooler and cleaned and turned up fan speed but still getting hot in the tranny on steep hills.
    Does the transmission have any adjustment for those gears? Thanks for the help.
     
  9. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions



    I am not an Allison expert but I have had my share of engine overheating. If your engine is not getting any warming then normal but your transmission is, you had better take it in to an Allison shop and have them do their diagnostics testing.

    Good luck and let us know what you find. :approve:



    Oh! Welcome to RVUSA. :cool:
     
  10. velocette

    velocette New Member

    Re: Allison Transmission Questions

    problem is i,m 400 miles from the closest Allison shop !!!!!!!!!!! :( :(
     
  11. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    Ok then. From what I have read, from the Allison Experts, as long as you do not reach 300 degrees F you are doing alright. What kind of temps are you reaching?
     
  12. velocette

    velocette New Member

    Re: Allison Transmission Questions

    Once had up close to 300 but mostly arond 260 -275 as i usually pull off for a cool down. Can,t always find a good spot though. Last one was heading towards Parump from Vegas and it hit just under 300. Not many spots to safely pull over. Engine heat has never been a problem.
    I guess i,ll pull the pan and have a look. Not sure about these auto trans! I know it has not holdback in 1st gear and seems to freewheel but will hold in second.
    Has a pac break buts thats like holding your hat out the window backwards compared to a retarder or jake. Ive driven logging trucks on and off highway but never had an auto trans in a big diesel before.
     
  13. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    At the top of this page is a person called "Allison Expert". For some reason he has missed your concern. Click on his Username and send him a PM. I am sure he will answer you back. Please let us know what the out come is. :approve:
     
  14. velocette

    velocette New Member

    Re: Allison Transmission Questions

    Thanks, i did send him a pm and have been talking with him.
    I did have a couple of over 300 degree hills which kept me on the edge of my seat so i don,t want to increase the stress level on every hill.
    just seem to get the runaround when i talk to local shops who give me stupid answers and want to pull the transmission and take a look. Lots of shops offer to take stuff apart to check for problems but don,t have experience with large automatics. Like most lawyers who state they practice law, not going to practice on me!
    I want someone who knows the insides and outsides and has confidence in their work.
     
  15. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    I have had my engine overheat on some of the hills but I do not think I have ever been over 180 degrees F in the transmission. Glade you got a hold of the Allison Expert.
     
  16. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    A while back dBarton and I was talking about increasing the hp to my CAT. dB said that I should run a test on the Allison Transmission before the do the hp increase. Does anyone remember or know the name to this test for the Allison.
     
  17. NikoFrost

    NikoFrost New Member

    RE: Allison Transmission Questions

    Hi Allison Expert, (and others)
    Great forum, I've learned a lot reading the older posts the last couple of days. My family and my wife's sister's family (seven of us and four dogs) are traveling cross country from Oregon to Florida. Right now we're stuck in the Dallas area.

    We recently purchased a 1993 Gulfstream 2000 on a spartan frame with a Cummins and an Allison MD-3060 with push button selector. It has only 41k miles, so it seems to have sat quite a bit, and by the condition of the interior, it had been at least couple of years. The seller drove it to my location with no reported problems.

    When I first drove it, it took a long time (15 min) for the "Do Not Shift" light to go off, even though we had over 110 lbs of pressure. The ECU behaved normally then. The second time I drove it, I went about 80 miles and the DNS light came on and off intermittently, while all the lights on the ECU blinked the whole drive.

    The next morning, the ECU would come on, flash for few seconds, then go out. I had not yet downloaded the "Allison_WTEC2_Manual" so I did not have a chance to check for diagnostic codes, but in retrospect it seems like a code 66 33, a Central Operating Processor timeout, and the flashing lights seem like a power error. (Can't say as I remember where in the troubleshooting manual I read that last part.) We started it several times that day, and near the end of the day, it stopped coming on at all. Then we pulled it from the dash and it seemed very hot, even for Texas.

    I then ran a voltmeter on pins B1, B2, B9, B11, and B18 of ECU connector B and got appropriate +12.8v and ground on those pins. The engine was off, of course- the engine wont start with the ECU pulled, but cranks right over with it in. With the ECU out, I'm not getting voltage from any of the other connectors.

    With some finagling of park and regular brakes, the light DNS light went off for a while, but it wouldn't shift into gear.

    I've yet to locate the fuse panel for the engine/transmission systems, but with the voltage coming in, it's seemed like a low priority, still looking though.

    I don't have a Prolink-9000 to read diagnostic codes, and I am wondering if one of the modern readers would do the job. I'm not sure what databus to use to talk to a early 90's MD-3060, is it J1939? Also, the WTEC2 manual may not be the right one for me to referring to, it's copyright is 1998 (5-6 years later) and several pins referred to in the manual's diagrams are blocked ("reserved") and don't go anywhere. (Pins A5, A8, A9, A17, A22, A25, A26, A27, A33 and A34 on ECU plug A and B3, B4, B25, B26, B29, B30, and B34- not present).

    So What do you think? I'm going with:
    1. New operator error.
    2. Bad fuse.
    3. Bad ECU.
    4. Frayed/shorted/broken wire to the ECU.

    So right now I'm hoping for 1,2 or 4!

    Please Help!
    And thank for all the input!
    Nick Frost
     
  18. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    I'm overseas and up late. I don't remember talking about running a test on the Allison before increasing engine horsepower. You might want to make sure the new HP rating is still within the transmission's ratings before going ahead with the HP increase, but there's no test on the transmission to be done I am aware of in this case.

    I still pop in every now and then to read some of the posts. Time for bed here.

    DB
     
  19. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    Glad to hear from you dB. I was thinking Agent 99 disappeared with you. Good to have you back. :approve:
     
  20. LEN

    LEN Senior Member

    Re: Allison Transmission Questions

    Think it sounds like corrosion in the wiring. I would check each plugin I could find from the trans forward and clean the connections. Also check for good grounds.

    LEN
     

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