Allison MH 2000 Will not go into 5th gear.

[PeterSchweizer]

2004 Monaco Cayman 34pdd 5.9 engine. While traveling today on Interstate 15 NB N of Ogden UT at about 68 MPH in Economy mode there was a downshift into 4th and it would never go back to 5th gear. NO Check Trans light or other service lights on,  Tried manually shifting up n down or pressing D to go back intro D 5 or Economy MODE on n off several times (NOTE:MODE light does go on n off as it should when cycling into Economy mode) .  Basically cycling it thru all the shifts no help. stopped repeated same, nothing, again turned coach off for several minuets no help.  Fluid level and temperatures normal. Had to drive the last 40 miles to Lava Hot Springs in 4th gear at 55 MPH.  

So any Suggestions? None of my coaches manuals Monaco or Allison discuss how or if possible to retrieve any codes- just says call Allision customer service, which I will do in the AM.

 Also anyone know of any good Coach  trans service  shops in Pocatello ID?

[PeterSchweizer]

Note: I tried to retrieve codes per Tom Cherry's resent response July 15 2023  post  of Shanners Mechanics life u tube viedo, but it never showed any codes?

[MurrayD]

Peter, when my alternator gave out on me I continued driving as the batteries went down. By the time I reached the next city voltage was under 9 volts and the transmission would not shift out of 6th gear. Is it possible your voltage is low?

[TW Racing]

Could be Transmission fluid leaked into the wiring harness connection causing a short. We had that happen a few weeks ago in Az and then it would not go into gear at all and no codes could be found. Hopefully that’s all it is as now we are told we need a new transmission, the tech found metal shavings in the pan.

wishing you the best of luck.

[PeterSchweizer]

45 minutes ago, MurrayD said:

Peter, when my alternator gave out on me I continued driving as the batteries went down. By the time I reached the next city voltage was under 9 volts and the transmission would not shift out of 6th gear. Is it possible your voltage is low?

VOLTAGE IS GOOD THANKS

26 minutes ago, TW Racing said:

Could be Transmission fluid leaked into the wiring harness connection causing a short. We had that happen a few weeks ago in Az and then it would not go into gear at all and no codes could be found. Hopefully that’s all it is as now we are told we need a new transmission, the tech found metal shavings in the pan.

wishing you the best of luck.

 

Just now, PeterSchweizer said:

will clean connectors in AM  thanks

 

 

Just now, PeterSchweizer said:

VOLTAGE IS GOOD THANKS

 

 

[cbr046]

Probably NOT your issue, but when my primary fuel filter started clogging the very first symptom was the Allison MH4000 transmission not shifting back to 6th after a slight load (any hill) while in cruise control (only).  Everything seemed fine in normal mode (cruise control off).  My best guess was the transmission CU was sensing limited power and keeping it in the lower gear.  It took a few trips and thousands of miles later but eventually the filter got so clogged I could barely make it up the slightest hill with ~10 lbs of boost.  I was new to the whole "diesel thing" at the time. 

My point is that the ECU and TCU might be limiting power for some abstract issue. 

- bob

[Dr4Film]

Hopefully the links below may help.

https://www.irv2.com/forums/f125/allison-mh2000-wont-shift-to-5th-gear-94921.html

https://www.rvtechlibrary.com/transmissions/1000_2000_operators.pdf

[Agpopp]

As a Neptune owner,  I'd like to hear how the issue was solved. Was the connection just cleaned and reinstalled?

[PeterSchweizer]

FIXED  follow up - Cleaned all 5 electrical connectors on transmission and it has been working for the past 1000 miles. Thanks everyone this is a great source for fixen!