Allison will not go in gear

Sure sounds like the brakes are stuck on.

The Allison transmission defaults to neutral at 11 volts. It could be in the charging system, and a low battery. A quick jumper from the house batteries (if at full charge) to chassis batteries, would discount that issue.

Has it been parked there a long time? If so then the brakes are probably stuck.
It can take some major pounding with a mallet to break them free.

Corkey05 wrote:
The Allison transmission defaults to neutral at 11 volts. It could be in the charging system, and a low battery. A quick jumper from the house batteries (if at full charge) to chassis batteries, would discount that issue.

Not Low voltage at all as OP says it goes into reverse

as two others have said sounds like the rear Brakes are stuck on
I have had that happen

A little more info received. She has been at the rally about 6 days. Part she disconnected was fuel sending solenoid (repeating what she told me). It would start, but not stay running, that's the reason for disconnecting. At this time she has tried moving it with that part connected and disconnected. Then she said that she thought it was low on motor oil, perhaps as much as 4 quarts. She just came back from Florida where she had a heart attack 6 weeks ago. Probably just not paying lose enough attention to maintenance issues due to health. I advised her about the brakes. Sorry I am not more mechanically inclined. I probably was not the best person to call upon for help. Thanks for the responses. She is getting motor oil in the nearest town and will see if that solves the problem. Her next step will be the brakes as you suggested and then a mechanic.

Tedtoo wrote:
A little more info received. She has been at the rally about 6 days. Part she disconnected was fuel sending solenoid (repeating what she told me). It would start, but not stay running, that's the reason for disconnecting. At this time she has tried moving it with that part connected and disconnected. Then she said that she thought it was low on motor oil, perhaps as much as 4 quarts. She just came back from Florida where she had a heart attack 6 weeks ago. Probably just not paying lose enough attention to maintenance issues due to health. I advised her about the brakes. Sorry I am not more mechanically inclined. I probably was not the best person to call upon for help. Thanks for the responses. She is getting motor oil in the nearest town and will see if that solves the problem. Her next step will be the brakes as you suggested and then a mechanic.

Motor OIl has ZERO bearing on the transmission working or not so ZERO
chance that's the problem

gutfelt wrote:
Motor OIl has ZERO bearing on the transmission working or not so ZERO chance that's the problem

X2. But, make sure she puts oil in the engine. Driving when it's 4 quarts low is not good.

Brakes wouldn't freeze up in 6 days.

5-6 years ago I was stuck out in Washington state where my coach would not move. It was an Allison 6 speed in my Airstream dp. I was towed to a local shop where they could not diagnose the problem. At that point We were looking at a few thousand dollars to replace the ecu. Someone on RV net sent me the name of a man that lives in PA. he speaks broken English (German I think) he is a wizard with the ecu and controllers for the transmissions he diagnosed the problem over the phone and I sent him the ecu. He had it back to me in 2 days all ready to go. I hope someone on the forum will read this and post a name or send a PM to the OP concerning his name and contact info. It was a huge savings to me as I think my total came to about $500.00

Assuming that the motorhome has an allison transmission, I suggest going through the diagnostic codes provided by the transmission shift selector

The allison 3000/4000 operators manual can be downloaded from the link below.

allison operator's manual

Fred