Allison Transmission Questions

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

  1. vtwinwilly

    vtwinwilly New Member

    RE: Allison Transmission Questions

    Just wanted to give everyone an update.

    Before I got a chance to pull, clean, and re-install the main connector as recomended by RWOODY (thx Woody), I had an appointment to get a new set of rear tires put on the motorhome before our annual Christmas trip. When I went back to pick up the motohome, the shift tower would not shift, and after a few seconds would go dead. I recall reading about this (someone else with a 94 Dynasty had the same issue) on this forum, and as I recall, they had to replace the ECU.

    Being a CoachNet member, I called and had the coach towed from the tire place, to Southwest International (the only Allison certifide facility I could find open on a Saturday). They found a short in one of the batteries which seemed to correspond with the low voltage fault from the ECU, so they replaced both, but this didn't fix the problem. They then sent the ECU out to be reprogrammed, being told that often when there's a low power fault, the ECU can loose it's programming. They reflashed the memory, and are now telling me the ECU is good (at least according to their bench test). While plugged into the bench computer, they downloaded several fault codes. All fell into the categories of Low Voltage, or input/output sensors.

    The ECU is now back at the shop, waiting to be re-installed in the motorhome. Hopefully that will get done tomorrow.

    Does anyone have any idea what would cause the ECU to power up for just a few seconds, then go dead? Turn the key off, and it does it again. My symptoms are identical to the fella on this forum with the 94 Dynasty, but I can't seem to find his post now, nor how his situation turned out.
     
  2. jljeeper@msn.com

    jljeeper@msn.com New Member

    RE: Allison Transmission Questions

    I have a 94 with a MD3060 and my ECU would die or go dead but it was related to the cold. It would be dead in the cold mornings and start working in the afternoon. I finally proved this to be the case by using a hair dryer to warm the ECU and it would eventually come on (2-3 min after applying heat) I could then take the ECU that was working in the warm afternoon and place it in the freezer for about 5 min and it was dead until it warmed up. This was repeatable every time with out fail. I sent the ECU to a repair facility somewhere in MN (I think). They fixed the problem that was temperature related, they said they had to resolder several surface mount components. When I got the ECU back it had several codes that I could not clear and that it didn't have before. I have a feeling that it may have been reprogrammed with the wrong code for my coach or who knows? It did seem to work fine though. I didn't feel comfortable with it in that state so I went and ordered a new ECU (several thousand dollars) I now at least have a working spare. Maybe it just needs a reflash after they worked on it. I wonder if your ECU would start working after it warmed up?
     
  3. rwoody

    rwoody New Member

    RE: Allison Transmission Questions

    i still think that you have a bad connection some where in that system

    the tech is not cking what the manual says to do if this is encountered

    ecu should have a stand alone memory that will not be erased. this is on the chip.

    have him pull the plug and clean with contact cleaner or at least look at it before he flashs the ecm....

    http://tktsales.com/ecu.html

    call this man with over 20 yrs of allison certs

    he will tell you the straight scoop! :approve: :approve: :approve:
     
  4. dbarton291

    dbarton291 Senior Member

    RE: Allison Transmission Questions

    I think that was DMR Electronics (Hibbing, MN?) that did your repair. I remember the discussions on this issue.
     
  5. dbarton291

    dbarton291 Senior Member

    RE: Allison Transmission Questions

    You are correct. The program itself is flashed onto a EE chip that does not lose its mind after a power loss, even an extended one.
     
  6. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Woody: How's your Wanderlodge coming along? I did not register to see the photos, but once I saw it the pictures were on a Wanderlodge forum, I see what you mean about your project being a lot cheaper than a new one!
     
  7. dbarton291

    dbarton291 Senior Member

    RE: Allison Transmission Questions

    Southwest International - are you in the Dallas area?
     
  8. rwoody

    rwoody New Member

    Re: Allison Transmission Questions

    coming right along

    hoping to start it today

    nice weather down here ....

    doing pin out on viw right now.
     
  9. vtwinwilly

    vtwinwilly New Member

    RE: Allison Transmission Questions

    Yes ... I am in the Dallas area. and now it's a done deal.

    Southwest International tested my harness and all sensors. They were all OK. They sent the ECU (or TCM as they referred to it) to Inland transmission to be re-programmed. Even after this was done the ECU was still flakey. They then programmed a new ECU/TCM (someone please educate me about the difference), and everything is now rock solid. I picked the coach up last night (Southwest is open til 10:00pm) and the transmission is performing flawlessly. I've only owned this old coach for about 18 months, and the transmission has never worked better. Shifts are silky smooth.

    We were/are planning to take off this weekend for our annual Christmas trip, and Eddie at Southwest really went out of his way to get us back up and running. I thought our trip was going to be cancelled (or at least postponed) but we're back on the road. Thanks Eddie!

    I'm going to go have a good time now. I'll stress about the $3500 in January.
     
  10. rwoody

    rwoody New Member

    RE: Allison Transmission Questions

    thats great that you got it repaired

    will drive mine tomorrow

    did the pin out from the allison manual and excited the tcm/ecm and got the magic N N

    i cannot understand that if the ing sense wire is to be used with battery/key on or not.
    they work togather and it forward and reverse with 6 light in the window

    this is after extending shifter wires and figuring out which wires that i really need form VIM and VIH and ECM

    if you want to see pictures please email this contact for them

    sorry they made a mistake and it was for everyone to view

    http://www.wanderlodgeownersgroup.com/forums/sendmessage.php
     
  11. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Ignition sense is powered when the ignition key goes to on. Battery is hot when the master switch is on and the ignition is still off.

    ECU = electronic control unit TCM = transmission control module

    If I'm not mistaken, Delco preffered the term ECU for just about any controller. I think the use of the term TCM for transmission controllers started with Delphi.
     
  12. rwoody

    rwoody New Member

    Re: Allison Transmission Questions

    so the key pad stays lit up all the time?????

    i have cat eyes untill i hook up the ing sense..

    hooked them both to bat power thru relay and drove it this eve

    have to rework throttle..gives it 1/2 and it still ran 65 hit all gears

    thanks!
     
  13. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    The key pad should not be lit up all the time. On the Allison schematics, a circuit labeled battery power (not just +) is battery power after the master switch, unless the schematic shows an oil pressure switch or something in between the battery and the component being powered.

    For example, wires 336A and 336B on interface drawing 07-047 are labeled battery power through a ten amp fuse. That's just what it means, battery power. 146 (346) are ignition sense, which tells the TCM when the ignition switch is on. Ignition sense "wakes up" the TCM. When shutting down, the shift selector stays lit until the signal from the engine speed sensor goes to zero.
     
  14. rwoody

    rwoody New Member

    Re: Allison Transmission Questions

    ok thanks for your clarification

    i will switch a couple around!
     
  15. rwoody

    rwoody New Member

    Re: Allison Transmission Questions

    done deal

    drove 750 miles home

    and 500 this weekend

    great conversion~!!!
     
  16. rjb11632

    rjb11632 New Member

    RE: Allison Transmission Questions

    I have an '89 Elite coach w/ a 3208 cat and an allison MT643. The problem is when I try to toggle back to neutral from drive the lcd goes blank for about 2-3 seconds and then right back to D. I can get under the rear of the coach and shift it manually but it goes all the way to R then it goes in to N with the toggle. I have done that three times. The third time it took three attempts to get to N from D, but it got me home without a tow. Can anyone help? Thank You.
     
  17. MavHD

    MavHD New Member

    Re: Allison Transmission Questions

    I have a 2001 Chevy 2500HD with a 8.1 and a allison. The truck only has 36000 miles on it. Today in Ohio we have a bad snow storm and coming to work in 4WD the Shift indicator did not show the correct gear, the service engine light came on, and shifting between gears when stopped is quite harsh. I was in "D" when I came to a stop, then when I went to go, the truck didn't respond, the shifted hard and the indicator showed 3rd gear. I wasn't in 3rd. I shifted back to park, the indicator is not highlighting the other gears. Right now, the truck seems to drive fine, but I have to count to make sure I'm going into the correct gear. 4WD goes in and out with not problem, but again its very harsh when stopped and shifting from P to D or to R. Have you ever heard of this?

    Thanks in advance.
     
  18. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Sounds like it may be the NSBU switch on the side of the transmission.

    It's best to see which codes are stored in the powertrain control module and the transmission control module. Once you know what those computers think is going on, you can look at the affected system(s).

    If you do not have access to a Tech 2(that's the scanner used to read the codes), you may want to pay a dealer or a local trans shop to read the codes for you. As always, access to a service manual will be a big help. You could always put an NSBU switch on it, but I can't absolutely guarantee that's the problem.
     
  19. Triple E

    Triple E Senior Member

    RE: Allison Transmission Questions

    I have a 1996 MD3060 6 speed automatic. I want to drain and refill the transmission with synthetic. Question: (a) Can I flush the tranny before the refill or should that be done at an Allison shop? (b) If this is something that I can do, what do I need to do in order to do a proper flush.
    I have a feeling that there is more than just pulling a couple of plugs. Thank you, -Steve
     
  20. jljeeper@msn.com

    jljeeper@msn.com New Member

    RE: Allison Transmission Questions

    I too switched to Transynd synthetic oil. What I remember is you can just change the oil as normal and refill with Transynd. What was stated by Allison for those who wanted the extra long change interval (5 year, I think) offered by using Transynd was that you needed to change your oil twice before it was considered to be 100% synthetic oil. I believe this was because that was the only way to get the mass of oil that resides in the torque converter diluted enough. Transynd is compatible with the regular stock transmission oil. I'm getting ready to change for the second time after 18 months, then I will be good for 5 years. If any of this is incorrect someone here will catch it.
     

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