Transmission won’t shift out of first gear.

[RVSSNAKE]

I put the bus in for new tires today.

went to pick it up and drove off the lot and it wouldn’t shift out of first gear.

I could shut it off and restart put in D and it would show 6 normal right but when I took off it stayed in first gear. 
 

ideas please!

I was only a few blocks from the shop so I took it back for them to look at tomorrow.

I did find a vacuum hose that ran from a chamber on the turbo that was chewed through would that cause that problem.

check trans light did come on when it was stuck in gear.

I am supposed to leave on Wednesday if I can get it working.

help,

[Dr4Film]

Take apart the transmission output speed sensor connector, clean both ends with a good contact cleaner then reconnect. That connector is located at the rear of the transmission. Check the manual for exact location.

You can also do a diagnostics check on your Allison keypad to verify the error code, output speed sensor.

Edited May 14 by Dr4Film

[Ivan K]

The hose should be for waste gate operation and would hardly effect shifting. You can plug it to get home and get more boost than ever or leave it and lose some for the time being.

[RVSSNAKE]

5 minutes ago, Ivan K said:

The hose should be for waste gate operation and would hardly effect shifting. You can plug it to get home and get more boost than ever or leave it and lose some for the time being.

Thanks for the idea and suggestion. 

30 minutes ago, Dr4Film said:

Take apart the transmission output speed sensor connector, clean both ends with a good contact cleaner then reconnect. That connector is located at the rear of the transmission. Check the manual for exact location.

You can also do a diagnostics check on your Allison keypad to verify the error code, output speed sensor.

The shop is going to run a diagnostic on it tomorrow, but I will let them know about the sensor.

Thanks for the suggestion.

[Mike H]

Dr4Film I suspect has the correct answer.  Your transmission has gone into 'LIMP' mode.  I had that happen to me.  Allison has mobile techs that can come to you and repair it.

[jacwjames]

When my transmission went into limp mode I was low on oil.  Not able to check the oil level with the shift pad I used the dipstick accessed by opening the bedroom hatch cover. 

[Mike H]

18 minutes ago, jacwjames said:

When my transmission went into limp mode I was low on oil.  Not able to check the oil level with the shift pad I used the dipstick accessed by opening the bedroom hatch cover. 

Don't trust that dipstick as that was added by Monaco, NOT Allison.  Once you get your oil level correct you might want to put a scratch across it to sort of calibrate it against your shift pad

[jacwjames]

1 hour ago, Mike H said:

Don't trust that dipstick as that was added by Monaco, NOT Allison.  Once you get your oil level correct you might want to put a scratch across it to sort of calibrate it against your shift pad

Long story short, I had a bad bad bad leak and did not know how much oil I had lost.  Rig would not shift out of 1st gear.  I had no idea how much oil I lost. 

Dipstick showed NO oil.  I added one gallon (yes 1 gallon) and check the dipstick with the engine idling for cold check.  Still nothing, so I added a 2nd gallon, still nothing on dipstick.  Finally added a 3rd gallon and the dipstick showed oil at correct level.  So I took it on about a 20 mile drive at highway speed, parked to let fluid settle down, and checked with shift pad  >>> OL OK.  

So desperate times call for desperate measures, dip stick was the only option I had. 

I was in UT at the time and called the nearest Cummins shop ~250 miles away and explained what happened, what I did.  Transmission wasn't heating up, shifted good.  They said I got lucky as the last 50 miles was pretty flat so the tranny didn't suck air, which would have toasted it.  I asked if they recommended a filter/oil change and they said the 3 gallons I added was half of a normal change so NO they didn't recommend an oil change.

Finished my trip, drove ~2500 mile home.  Took an oil sample and sent it in for analysis and it came back good.  I got lucky. 

You gotta do what you gotta do. 

[RVSSNAKE]

On 5/13/2024 at 7:40 PM, Dr4Film said:

Take apart the transmission output speed sensor connector, clean both ends with a good contact cleaner then reconnect. That connector is located at the rear of the transmission. Check the manual for exact location.

You can also do a diagnostics check on your Allison keypad to verify the error code, output speed sensor.

You were correct, it was the sensor. 

I let the shop know to look at that sensor first thing the next morning and that is what they looked at right after replacing the vacuum line.

It was the issue.

They took it out and cleaned it off really good as well at the connector.

Put it back in and all was good again.

They did suggest replacing it due to its age.

Thanks for the recommendation. 

[Dr4Film]

Glad that it wasn't a bigger problem for you!

Safe travels!