Allison Transmission Questions

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

  1. Leroy

    Leroy Junior Member

    where can I find a preasure gauge and instuctions?
  2. dbarton291

    dbarton291 Senior Member

    Now we're getting somewhere. If you have a code that says the TCM needs to be replaced, that can be the cause of everything you are experiencing.
    The ratio codes that keep coming back mean the TCM expects to see the transmission in the correct ratio after a shift, and it's not. That can be either a defective TCM, or worn out clutches. Since it's so inconsistent, the first thing I would do is replace the TCM.

    Just in case though, before spending any money on a TCM, I would take a real good look over the wiring harness and see if there's any damage to the harness, or corrosion in the connectors.

  3. dbarton291

    dbarton291 Senior Member

    Got to thinking. Just had to ask. This isn't one of those flooded vehicles from the east coast we're seeing come on the market now is it?
    Water in the TCM and corrosion in the connectors would do this kind of stuff, too.

  4. dbarton291

    dbarton291 Senior Member

    I don't mean to be a poop, but if you don't have, or don't know where to find a pressure gauge set, and you don't know how to use them, leave that to the pros. It's not that simple. Check your harness out thoroughly. The TCM is the next suspect in my opinion.

  5. Leroy

    Leroy Junior Member

    as far as I know this was a Oklahoma owned truck. I did pull the connectors from the tcm a while back and checked the connectors and they looked clean.
  6. Leroy

    Leroy Junior Member

    I know where I could find pressure gauges but no I never had a situation where I had to use them before and thought maybe you had a suggestion of a good set and where to get them from. I am mechanically inclined and not afraid to learn what I need to know about using them or reading instructions to do the job correctly. I think if I am not wrong everyone has to learn the "how to" at some point :) anyway I appreciate your advice and knowledge. the main reason I am here is to save money rather than taking it to a shop if I can do it on my own. If it comes down to changing a transmission I can do that. And here is a new one that just happened the other night driving home. I was cruising along when things started acting up again. but this time it wouldn't let me set the cruise... so when I would take off from a stop and it would change through the gears, I would get to hwy speed of 65mph. as long as I held my foot on the throttle everything would be fine but if I even let up on it just a little it would slip out of gear and back into neutral. then I would have to come to a stop and do it all over again. Think I will end up getting a new tcm and if it still does it I think it will be a rebuild on the tranny. if it goes to that point what kit do you recommend? the only heavy thing I would be pulling with it is a 11k camper.
  7. dbarton291

    dbarton291 Senior Member

    OK. Good. The 1000 has a main pressure tap right down next to the oil filter. Hook up a 300 psi gauge there. It should maintain about 150 psi if the pump and clutches are in good shape.
    Take a good look at the condition of the connectors at the three speed sensors. The input speed sensor is the front one. The turbine speed sensor is behind that one. The output speed sensor is on the rear cover. Inspect the harness thoroughly for evidence of damage.

    If you have access to a copy of Allison DOC you can watch the speed sensor signals as you drive to see if one of them falls out or is erratic.

    I've been through a lot of these situations where the symptoms seem complicated, but it turns out to be something simple that is easily overlooked.

    If you do go for a rebuild, since it has 200K on it I would use a master overhaul kit that includes that clutches, bearings, bushings, etc. The genuine Allison kit will have the highest quality parts, but it's likely to be expensive. There are several aftermarket choices available. A service manual would be a good investment, too.

    If you don't want to go through all the labor of rebuilding, there are also rebuilt transmissions available from several sources. The Allison ReTran has a good warranty but again, if cost is a big issue you may look at the aftermarket.

    You can go to and use their service locator to find an authorized service outlet near you.

  8. Marvin/Bounder92

    Marvin/Bounder92 Junior Member

    92 Bounder with Allison transmission model 452

    I would like to ask how you set the kickdown on the transmission from the throttle linkage on a Model 452 Allison Transmission?

    Thanks in advance for any information you can give me,
    Marvin Williamson
  9. dbarton291

    dbarton291 Senior Member

    Do you mean a 542? There is no Allison 452.
    There's not really a kickdown per se like on some cars. There is a modulator that may be a mechanical linkage. Is that what you're referring to?
    If that's what you're referring to, try this link:

  10. Marvin/Bounder92

    Marvin/Bounder92 Junior Member

    We had the numbers on the Allison transmission transposed, all right. Thanks so much for the link. I'm sure it will be a big
  11. Marvin/Bounder92

    Marvin/Bounder92 Junior Member

    Only part of my message posted. It should have read:

    We had the numbers on the Allison transmission transposed, all right. Thanks so much for the link. I'm sure it will be a big help!

  12. jasper2222

    jasper2222 Junior Member

    allyson man, I have a Duramax 2003 automatic allyson transmission. I have been getting erroneus reading on my cab temperature gauge. The transmission has gone into limp mode twice when the gauge has shown hot fluid. The fluid is not hot. I have changed out the internal transmission temperature sensor but it did not correct the problem. I get a code 711 which just means that there has been a major variation in temp. swings. I asked on another web site and that person recommended checking the ohm reading on the wires going to the TCM, but that is getting a little out of my expertise. Should I just replace the TCM and hope that is what it is or do you have any other ideas. Sometimes the cab gauge does not read at all. thanks, Richard
  13. ANT

    ANT Junior Member

    Hi Allisonman. greetings from England. I have a problem with an Allison 2000 series, fitted to an Optare Solo mini-bus (not sure if you have them in the States). Basically I sourced a replacement unit and once fitted, the engine stalled as soon as drive was engaged. All electrics were disconnected from transmission and fault still occured. When propshaft is disconnected transmission shifts fine, lock-up engages once 3rd is selected (had the allison diagnostic connected).To cut a long story short, torque converter (twice), oil pump and valve body have been changed, though no obvious fault with was found with any of them. The transmission has been stripped and all running clearances are ok. with no sign of wear/damage. yet the problem with stalling the engine persists. If you have any idea as to what the possible cause could be, any advice would be greatly appreciated


  14. dbarton291

    dbarton291 Senior Member

    OK. Let me get this straight. With the propshaft disconnected, you select drive and you get 1C. The transmission shifts correctly. Lockup come in in third gear. That means the transmission controls are functioning correctly.

    You have Allison DOC connected, so you see the TCM command lockup.

    If you are SURE the engine is healthy, it may be the lockup clutch is not being commanded ON by the controls, but is being applied by an internal leak to the trans somewhere. That won't show up watching the solenoid commands in DOC. You have to compare engine speed to turbine speed.

    Since you have Allison DOC, look and see if engine speed and turbine speed are exactly equal as the output is turning. That will tell you if the lockup is being forced on by an internal leak.

    You may have to leave the propshaft in and raise the drive wheels to put a slight load on the output to make sure whether or not the engine and turbine are turning at exactly the same speed in drive. If you find engine speed exactly equals turbine speed, you need to return the transmission to where you sourced it for an exchange. It may be a main case, torque converter housing or control module issue that isn't readily visible.

    If you leave the propshaft in, raise the vehicle, run the engine in drive and can see an obvious difference between engine and turbine speed, the problem is not the transmission.

    Just for my curiosity, why are all those parts being changed out and the unit disassembled? What a waste of time. If it's an exchange, why not just get another one? Who are you dealing with?

    I am familiar with Optare buses. I don't believe we have them in the States in any quantity. Good luck.
  15. dbarton291

    dbarton291 Senior Member

    Honestly, for much less than the cost of a TCM you can take it to somebody that has a volt ohm meter and a wiring diagram and they can check the resistance of the temp sensor circuit. At the same time, they can check the wires in the temp sensor circuit for shorts to other wires in the harness and shorts to ground. I would recommend you get a volt ohm meter and learn how to use it. If you've got the mechanical aptitude to replace an internal sensor, doing minor electrical troubleshooting shouldn't be too hard to learn. It's easy and doesn't cost a lot. It will save you tons of money and time.

    Do you have a power chip in the truck or anything? Like an edge?

  16. jasper2222

    jasper2222 Junior Member

    allison man, In regard to temp. gauge malfunction, I did have an edge EZ but it was only set on the lowest setting. I have removed it since having these problems, but the problems still exist. Will work on my electrical troubleshooting. I don't have a regular service person that works on my truck, Will search around and do some of the checking my self. will keep you posted. Thanks, Richard
  17. ANT

    ANT Junior Member

    Hi Djbarton, thanks for the reply. The replacement unit was from a mate as a favour, so between us we're trying to suss out what the problem is. There's no time pressure involved so we thought we'd have a 'play' haha!
    The turbine and engine speeds seem identical, ( how accurate are the readings on the Allison DOC? As there is an occasional slight fluctuation / variation between the two.
    Looking at the hydraulic circuit diagram, when there is TCC pressure in the torque converter, the pressure on the other side of the lockup plate is exhausted. So am I right in thinking that the fault could be caused by a lack of pressure in the converter-in circuit not keeping the lockup plate disengaged?
    A possible internal leak in the main case/ converter housing you said, is this a common fault? The mating faces all look ok but are there any areas in the castings that are susceptible to leakage? My mate says he's never come across this fault before ( he said he's done a few of these transmissions, but usually works on Allison AT series). Thanks again for your reply

  18. dbarton291

    dbarton291 Senior Member

    Ah okay! I got it now. Friends having fun. I spent some time in England in the 80s and got quite a taste for the county ale in the pub my friend and I hung out in. We were in Grantham. It was a pale ale. Very good. She was a folk singer. An interesting gal. She also rang the church bells as a hobby.
    You are correct in your thinking. A lack of pressure will prevent the LU clutch from disengaging.
    Those kind of leaks are not common that would cause what you are experiencing. I really can't give you a specific place to look.
    The best advice I can give at this point is to change the TCC solenoid. Maybe it's mechanically stuck on.
    Then check the valves and springs in the bores for the converter relief valve and the converter flow valve to see if they're the right parts and that there's no broken springs, stuck valves, etc.

  19. Oldgoatfarmer

    Oldgoatfarmer Junior Member

    Hello I need some help with a MT654

    First of all Thank you for your help with those of us in need. I love my Greenville SC Allison dealer they are #1 in my book great service. I am trying everything I can before I make the call for a service call. My Mt654 is stuck in first gear and no reverse. Is there anything I can check of possibly fix as my transmission is not under any warranty.

    I have checked the levels no contamination and correct levels checked when warm operating temps. I was told since it had been sitting for some time that it happens. I am planning on changing the filter/fluids myself. After the tow bill I am trying not to call the service guys and they do 1 or two things and they are done. I kind of feel like a dummy if I cannot rule it out first. I thank you for your time.
  20. dbarton291

    dbarton291 Senior Member

    So you can start the engine in neutral and the vehicle doesn't move?

    When you select drive and hit the fuel, what happens? No upshifts?

    When you select reverse, do you get a neutral, or is the transmission locked up and the vehicle won't move?


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