Allison do not shift warning

Discussion in 'Class A / Diesel Pushers' started by swhite, Aug 8, 2009.

  1. swhite

    swhite New Member

    95 Gulfstream with a 6 speed allison auto (350 cummins) 85K miles.
    About a month ago did a 1000 mile trip with steep hills (WV) and the RV ran flawlessly.

    Yesterday taking it on a short run to the lake for the weekend (about 60 miles) all flat terrain and got the do not shift warning buzzer in 5th gear. Pulled over, reset the ignition (turned off and back on) and it went away.
    About 2 miles down the road, same thing hit 5th gear and got the do no shift warning.
    Temps were fine (water and trans)

    Pulled over again - Read the code 55 87 Clear the code out and called the tow truck (short tow since we are close to home)
    While waiting for the tow truck - I noticed that I code get the code every time if I put it in D move forward a couple of feet, stop, select N then go to R and while backing up I would get the same DNS warning light.

    Tow truck shows up - finds a couple of the battery cables loose on a solenoid located on the frame rail in front of the trans on the drivers side. Said that may be causing the issue (power cutting out to the controller) - we tightened them down and it seemed to go away.
    Drove it for about 10 more miles with no issues then got the DNS light again in 5th but different code 32 55
    (C3 pressure switch in open in 5th)
    I parked it and just had it towed to the shop

    We haven't owned this particular RV very long but it appears to have been taken care of. Runs strong, shifts nicely, no leaks, drives very easily but this warning issue has me perplexed.

    Any guesses?
     
  2. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    Likely culprits are the wiring to the C3 pressure switch, the C3 pressure switch, or the internal harness. I'd do those basics first.
     
  3. swhite

    swhite New Member

    Re: Allison do not shift warning

    Well we ran the tests. All switches checked out.
    Found a ton of metal in the bottom...... :(

    Looks like it it time for a rebuild............

    And it is a Cummins 300 not 350.....Just to be correct on the engine.
     
  4. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    Bummer. If there's a lot of metal in the bottom, that does sound like it's time for a rebuild. What may be happening is the C3 pressure switch is opening due to lack of clutch pressure, thus the code.

    On the bottom of the control module, there is a pressure tap for each clutch and the casting is labeled. It's probably too late now because it's already apart, but a gauge could be put in the C3 pressure tap to monitor the clutch pressure to see what it's doing.
     
  5. swhite

    swhite New Member

    Re: Allison do not shift warning

    Yep it is too late.
    That is pretty much what is happening.
    It will shift perfectly right up until the trans warms up - then it begins to loose pressure. Loss of pressure then you get the code.

    We are going to put a re-manufactured trans in that has a warranty. Found one for $3950 with a 1 year P/L warranty.
     
  6. swhite

    swhite New Member

    Re: Allison do not shift warning

    Interesting update.....
    Confirmed the transmission was pretty much gone, although it didn't shift bad.....
    However, we put a brand new trans in it and got the exact same code....
    Tested the harness and it passes.....
    Now on to the ecu ....nice.
     
  7. swhite

    swhite New Member

    Re: Allison do not shift warning

    ECU past test by allison - Put it back in and still get the same error.... Tested the harness again - all passed -
    Has everyone perplexed....

    Does anyone have any suggestions?????
    Replaced Trans with a full rebuilt allison dyno'd trans
    ECU pass
    Harness passes
     
  8. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    In troubleshooting the chassis harness, I have seen more than once, terminals spread from the probing done when checking for opens, shorts between wires and shorts to ground. I would perform a tension test on the relevant terminals. Take a mating terminal and insert into the terminal in question. Make sure it's a tight fit. If mating terminals are not available, it can be done visually looking for damage, but it doesn't take much damage for one of those terminals to lose its tension.

    Who tested the ECU and what did they do?

    How are you testing the harness?

    Looking at the WTEC III schematic, one side of the C3 switch circuit is wire 135. That's a ground that's shared with the TPS. Make sure that part of the harness is checked for opens, shorts to ground and shorts between wires also. When I check out a harness, I check all circuits for opens, shorts to ground and shorts between wires just to be safe.

    Has the internal harness been checked for those three things also?
     
  9. swhite

    swhite New Member

    Re: Allison do not shift warning

    It's WTEC II not the III
    ww williams tested the ecu - they are our Allison people in this area.
    Ohm tested the harness plus opens and shorts, etc. as well as ran a complete new harness - still got the same code when you hit 5th gear.

    Are you talking about also testing the internal harness of the trans?


    Interesting development today though. When they put a different ECU in, it came up with a Throttle Position Sensor error and would not shift at all.

    Tested the TPS and it was bad.

    Will put a new TPS in tomorrow of course the same day I am scheduled to take the RV to NM......

    Could it have been the TPS all along or is this just another problem not related?
     
  10. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    Very confusing. If the TPS is bad, there should have been a code 21 XX all along. I am referring to the internal harness in the trans. I'm getting ready to leave the country on business for a while, I'll try to check back when I have a chance.
     
  11. swhite

    swhite New Member

    Re: Allison do not shift warning

    I was gone for a week to NM as well - Without the RV :(
    The trans was a drop and swap with a fully dyno'd trans by allison. Not to say it couldn't be the internal harness, just not likely since it was tested prior to install by allison.
    Haven't gotten the report back yet as to whether the TPS sensor was the problem all along. Should know something on Monday.....
     
  12. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    Back from Asia last night. Glad to be back in the good ole US of A. I was dyin for Mexican food.

    Anyway. Since the trans is a rebuild, it could have a problem that developed post dyno test. I think I'd start from scratch in the troubleshooting. I wouldn't assume the trans is 100%. Switches can fail, intermittents can become hard failures.

    If the service outlet KNOWS the TPS is bad, it should be fixed first. I'd be real curious how they determined the TPS was bad. There should have been a 21 XX code all along. I wonder if they found a problem in the wiring to the TPS instead of a failed sensor.

    Even after eating all kinds of stuff that looked bad and smelled worse in Asia, none of that stuff killed my curiosity about this one. I'm really interested in what you find out.

    Keep us posted!
    DB
     
  13. swhite

    swhite New Member

    Re: Allison do not shift warning

    They found the TPS issue when they used different ECU.
    With the different ECU (one they used for dynos) it didn't have any other codes after they replaced the TPS. BUT the apparently the dyno ECU was only programmed for "testing and not road running", new to me. Now they are waiting for the ECU with the correct programming to see if it is fixed completely. Should know on Weds.
    They said when they put the original ECU it still fails the C3 and never did get the TPS warning. The original ECU has been tested and retested and always passes. But it is the older version WTEC II and they didn't seem real positive on the ECU testing procedure (this being Allison techs not the local guy).
    Can you say crap shoot?
     
  14. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    I don't believe Allison ever released to the field any test procedure on the ECU itself. To fully test one is way more complicated than most folks believe. That's probably why they don't seem certain on this one. Trying the ECU from their dyno actually was a good idea. I wonder how the original one was tested.

    There are test cals for ECUs that are very different from the ones used in a running vehicle. Shift points, inhibit functions, etc. are normally modified for the dyno.
     
  15. swhite

    swhite New Member

    Re: Allison do not shift warning

    I'm just relaying the information here.
    I spent many years building class 8 trucks (KW) and every one we dyno'd was with the factory spec'd components. So the dyno testing ECU makes no sense to me. I would rather just get a known "good" matching ECU and use it. Plus if the original ECU passes why do they still think the original ECU is bad? It may be that they quit using the WTEC II years ago and no one really knows for sure on the II series what is "right".
    They sent the original ECU back to Allison for "testing" in the beginning. In which it passed just fine according to Allison. Course they are also are the same ones saying the ECU might be the problem.
    I get the impression no one really knows what is going on here. Including Allison. It really shouldn't be this difficult. Seriously.....
    I have pretty much lost all confidence with allison and the local shop, but when you are in this far your options are limited.
    If it turns out to the internal trans connectors/harness on the new rebuild, then I guess the trans rebuild company can foot the bill for all this extra time and labor...
     
  16. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    I know you're just relaying info. I appreciate that. I'm sharing what I know to try to get you the straight skinny. Some of the info you're getting doesn't make any sense.

    The dyno you're speaking of used in vehicle assembly is a chassis dyno on which an entire vehicle is tested. The local Williams shop may be referring to a transmission dyno, which is just a test stand for the transmission only. It has to be capable of testing many types of transmissions and the ECUs used for transmission dyno testing have some of the safety features disabled, and may contain shift algorithms that are not suitable for use in a vehicle.

    I can speak with authority when I tell you no ECUs go back to Allison (Indianapolis) for testing. That statement that they are telling you about this ECU being tested by Allison makes no sense to me. There is no return/test for the original ECU to "pass".
     
  17. swhite

    swhite New Member

    Re: Allison do not shift warning

    I think they said they sent the ECU to WW Williams in Columbus,OH. They offer the testing of ECU. I know nothing more than that. I would think that since they got the dyno ECU from the williams - that williams probably used the original ECU on the dyno to "test" and it worked. That is merely a guess but what I was thinking.
    We used to dyno the complete chassis but I would still think you would need to dyno the trans with the proper ECU rather than a non-standard type. For example maybe the rebuild works fine on the WTEC III ECU or the Dyno version but not the WTEC II - don't know.

    I was planning on going back to NM on Friday AM and figured they would have surely had the RV completed by now since they have had it for over a month...... Boy was I wrong...
    If I need to get a new WTEC II can I just use the WTEC III instead?
     
  18. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    Any update on your situation?
     
  19. swhite

    swhite New Member

    Re: Allison do not shift warning

    They are about ready to give up....
    The reprogrammed ecu gave the same code as the original.
    They checked the internal harness even replaced the c3 pressure switch (Allison sent them one).
    Allison did verify that the original transmission was fine and did not need to be replaced. Nice huh?

    I asked him to check the connectors 1 more time... He said they would and let me know today....
    I am thinking it is in the connector.
     
  20. dbarton291

    dbarton291 Senior Member

    Re: Allison do not shift warning

    Who verified the original trans was fine and how did they do it? Just like what they were telling you about the ECU, Allison doesn't do that.

    Who is this local shop that is doing all this work and telling you this stuff?
     

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