Allison Transmission Questions

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

  1. dbarton291

    dbarton291 Senior Member

    450 kPa is only 65 psi at idle. Should be at least 150. You may have a pump that is worn and not producing enough pressure, or a worn forward clutch. The clunk you feel is probably forward clutch dropping out and then re-engaging. Most likely not first clutch. Something is giving you low main pressure.

    the modulator, if it's a mechanical cable should be moving smoothly from idle to wide open throttle. The transmission may be a reduced modulation calibration so you don't feel any difference in the shift points until you are near wide open throttle.

    Hope this helps. The pressure thing is bad news, but 65 psi is too low.


  2. dbarton291

    dbarton291 Senior Member

    Check the modulator cable adjustment. That will have an effect if the cable is pulled out toward wide open throttle when the throttle is really at idle.

  3. Roy SDA

    Roy SDA Junior Member

    Hello am newbie,
    Please help us.
    My Kenworth truck with Cummins ISX 475, Allison transmission RDS 4500 , some of days (the period of one month) we obtain problem of "double CAT EYE", is that We do is the following:
    1.Inspection thoroughly "Wiring Harrness" for ECM Engine, Cabin CECU, Shifter, Allison TCM, all Solenoid, Pressure Switch, Switch Solenoid Allison, all Connector.
    2. Inspection of all Control valve jammed or damaged.
    3. CAN Inspection line at all locations (Engine, Shifter, CECU, Allison TCM: all resistance of 60 Ohm.
    3. Replace with a new Allison TCM with the same program.
    4. Try TCM, Shifter, CECU, Throtlle Pedal from the damaged unit to unit operating (running) the result is all the components are working properly.
    5. Allison oil pressure test on the standard result: approximately 240 psi.

    Of all these measures did not seem damaged components and all measurement results are good.
    So far Diagnostic Tool (Noregon / Nexiq) still can not connect, but for Cabin CECU (ESA) and Cummins INSITE can be connected.
    I do not know exactly what to do, seems to have been a maximum.

    Help ideas, suggestions from comrades RV Talk Forum so we look forward, thank you for your time and attention.
  4. Chris_Sg

    Chris_Sg Junior Member

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  5. michaelsmd

    michaelsmd Junior Member

    Hi Allisonman, I appreciate your offer to answer questions about these transmissions!

    I just purchased a 1993 motorhome that has an Allison md3060 and the shifting seems to be taking longer and is harder than I am used to. Maybe you can tell me if this is normal or not? My only point of comparison is a 2007 motorhome with an allison, which shifted much faster and smoother.

    The motorhome is a 1993 coachmen royal rd, with a cummins 8.3 250hp and I would guess that it weighs about 23,000 lbs. I have experienced all this driving on flat roads in 100+ degree weather. There are no warning messages and the fluids/temps are all good.

    The transmissions seems to shift 1-2 before or around 1500 rpm and the rest of the gears seem to change around 1700 when under light throttle. This all works fine, but the shifts can seem hard at times and they almost all take several seconds to change gears. Almost like I can feel it coming out of gear and then (2 or 3 seconds later) I feel it shift into the higher gear with a noticeable "kick". This happens every time under light/medium throttle, but under full throttle, the shifting is much faster and almost seems smoother.

    Thanks for info or help anyone can provide!
  6. dbarton291

    dbarton291 Senior Member

    Does the engine RPM increase more than 200RPM or so between shifts?

  7. dbarton291

    dbarton291 Senior Member

    There can be many causes for shift selector cat eyes condition. I recommend you communicate with the following company so you can discuss all the details with someone knowledgeable on Allison 4000 series transmissions:


    Maju Engineering Services
    Allison Direct Dealer
    79 Jalan Pendamar 27/90, Section 27
    Shah Alam , Selangor 40400

    I have been to Maju and they were very knowledgeable.

  8. dluv

    dluv Junior Member

    Hey man, I hope you can help me? I have a 2001 Chevy HD Crew Cab 3500 with an 8.1 liter engine. I'm not sure what Alison I have in it? Here is the problem I was driving home from my job to my house, witch is about 25 miles when I got off my exit the tranny if my truck was stuck in 1st gear for some reason. I was going about 40 mph at about 3500 rpm. After my son's 2 hour baseball game I got into the truck to see if I could make it home and the truck drove totally normal like nothing happen. The truck was shifting fine......I don't know what to do I took the truck to 2 different transmission shops and they said oh you need to rebuild you tranny.

    The funny thing is the guy at AMCO showed me the codes that came up. The first code was an electrical code in the tranny that failed and the second code was a tranny default code because the tranny failed and was stuck in 1st gear? Any suggestions
  9. dbarton291

    dbarton291 Senior Member

    I'm afraid from the description you have given, I can't help very much. You first need to find out which transmission you have. The Allison transmission was an option in that truck. You may not even have an Allison.
    The description of the codes you gave doesn't make any sense either.
    If the electrical codes referred to specific circuits, I would make sure those circuits have no opens, short or shorts to ground. Sounds like an electrical intermittent may be the cause, but I can't be sure from what you've written.

  10. donz63

    donz63 Junior Member

    I have a 2001 3500 4x4 duramax with an allision tranny .pulled 5th wheel all last summer no problems .This year pulled it for first time and tow haul button did not work .I found the problem broken wires at shifter base like i find out most do. However there was a clean cut . and it has two wires inside the orandge cover .I have soldered the back together . and tow haul now comes on.I then had tranny flushed for maintanace themechanic stated the tran fluid looked good but we did it anyways for maintanance .He put in bg synthetic fluid. Now I have pulled it twice and the tranny has went into the limp mode were it locks it in third gear I think it is third anyway .It codes 730 and once it coded 700 as well but only once on the 700. Is it possible to have crossed the wires on the tow haul that would be causing thois or is the bg synthetic fluid a bad match for the allision. I went from no problems to this for no apparent reason .The are the only things that have changed . Any suggestions
  11. LEN

    LEN Senior Member

    If were me, I took a quick look at the chart on the BG and saw nothing about your trans, I would be going to transynd fluid the Allison recommended fluid. Or do some research on the BG and see if it is a cross over.

  12. Leroy

    Leroy Junior Member

    Hello Allison man. I have a 2004 Chevy silverado 2500 4x4 with the duramax and Allison transmission. When I am driving at slower speeds or slowing down it seems that the transmission switches to neutral and then it sounds like it is whining like it is trying to go into hear. If I shut the truck off and let it sit for a few minutes and restart it it goes into gear and goes. It does this in reverse sometimes to and the digital on the speedo says shift inhibitor or something along that line. I change the NSBU switch but it still does it randomly and it's a pain when it happens at a red light with traffic. Any other ideas what the problem could be? Thank you Leroy.
  13. dbarton291

    dbarton291 Senior Member

    Hmmmm. I wonder if you're hearing the lockup clutch disengage but that doesn't happen in reverse. If that's not it, my gut reaction is to check for trouble codes and check the oil and make sure oil level is good. Then put the pressure gauges on it and recreate the problem to see if there's a pressure problem.

  14. Leroy

    Leroy Junior Member

    If it is the lockup clutch disengaging what causes that and how do you fix the problem?
  15. dbarton291

    dbarton291 Senior Member

    The lockup clutch is supposed to disengage at low speed. That puts the transmission back in its mode where the torque converter is acting as a fluid coupling. That's how an automatic works. It's in fluid coupling mode (or vortex flow) at stop so you don't have to have a clutch pedal.
  16. driller2948

    driller2948 Junior Member

    Hello Allison man! I have a new 2013 GMC Duramax with the Allison 1000 auto transmission! With 1,000 miles on the truck I pulled my 12k 5th wheel into Colorado from Texas! Pulling some decent 6% grades with a GCWR 20K. With ambient temps running around 90 deg. I saw engine temps of 200 -210 and tranny temps of 154 – 175. However my brother-in-laws 2007 GMC Duramax with the Allison 1000 auto transmission with a GCWR of only 18K! Engine temps of 210-230 and tranny temps of no less than 210 and peaked around 230! Why such a big difference? O’ the 07 only has 45k! The dealer he contacted said those temps were well in spec and he has nothing to worry about! I’m not so sure about that, what do you think?
  17. dbarton291

    dbarton291 Senior Member

    I wonder if your 13 is reading sump temp and the 07 is reading temp to the cooler.
    In any case, even for to cooler temps (which is the hottest in the system), those are well within spec. Dexron is good to 300 F.
    After 300, Dexron begins to break down. And fluid life is inversely proportional to temp. The hotter it runs, the shorter the life of the fluid.

  18. Leroy

    Leroy Junior Member

    sometimes it disengauges when I am driving at slow speeds then its like it in netrual and wont engauge to take off and I hear a whining sound so when I go to put it in park it kind of make a loud grinding sound. I then shut it of and when I restart it it goes for awhile but does it again. if I give it throttle it just makes a faster whining sound but still wont move. sometimes when I am taking off from a dead stop to get to highway speed it also stalls between shifts and acts like it is in netraul then I have to pull over and go through the shut off and restarting engine to take off again. some times it seems to drive normal and other days are a pain in the butt. could it have anything to do with the powertrain modual not sending it the right info for changing gears?
  19. dbarton291

    dbarton291 Senior Member

    Assuming the fluid level is good, it sounds to me like it's time to put the pressure gauges on it and find out what's going on in the transmission itself. How many miles are on it?

  20. Leroy

    Leroy Junior Member

    It has over 200k on it. just bought it a couple months back. I checked the fluid level and that is full. I havent checked the transfercase fluid level yet though. Ive used the code reader on it and and have cleared all the codes and I get a code that says my tcm needs replaced or reprogramed another says read speed sincer and sometimes I get a bad ratio code. and when I clear each time it gives me a different bad gear ratio. one time it may be 1st gear another time it may be 4th or 5th. when I take off and drive down the highway and set the cruise it seems to be fine but when I let of the peedle sometimes it just goes into netraul and I have to pull over and shut off truck for a couple minute and when I restart it it works again for a while. I've read a lot of other forums and tried to pin point the problem but with all the different sulutions its kinda hard to know where to start. one person said if the transfer case is bad that would cause it to slip into netral also. and if the rear speed sincer on the transfer case is bad that would cause it. or a clutch sliping. kind of confusing. seems that the cluches work fine going through all the gears, its just when I let off is when it goes into netrual. for example if I am traveling 65mph and come to a town where the speed reduces to say 35. its almost like it hangs up between a gear rather than making a complete shift. I understand that 1st and 2nd run off the turbine, but it does this even in say 3 and it seems like 4th to. from what I understand it is suspose to be locked in in 3rd gear and up and runs off the turbine in 1st and 2nd gears. somedays I wont have a problem with the shifting and others are a nightmare. lol.

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