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Old 09-28-2020, 04:57 PM   #1
New Member
Join Date: Sep 2020
Posts: 1
Tranmission won't shift into gear

Hi, my name is Hank, and I own a 1999 Blue Bird school bus. 8.3 liter, 12 valve Cummins engine, and the transmission is an Allison md-3060. The problem I'm having is the transmission will NOT shift into gear. What I think I've learned so far is that I have a shift inhibit problem. My transmission has a push button shift selector keypad which blinks D and R respectively, but will not shift into gear. When I push the up and down arrows simultaneously to read the codes it does not give me any, which the Allison dealer told me over the phone that means the transmission is not going into gear for some other reason. I'm not sure what is causing this shift inhibit. Apparently it could be a number of things, one of which is engine speed or transmission output shaft speed but those things seem to be fine. Can anyone help me figure this out?
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Old 09-28-2020, 05:08 PM   #2
Bus Geek
Join Date: May 2009
Location: Columbus Ohio
Posts: 13,905
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
someone else started a thread like this.. did you recently remove a wheelchair lift or such? these transmissions have a mode that will inhibit them from gpoing into gear if it thinks a wheelchair door is open or the lift is deployed.. sometimes auto neutral is applied when the school lights are on so if you removed your school lights make sure the wires you cut didnt short against something.. since theres no codes im going at it from the idea that the transmission isnt errored out..

does the display show anything? 2 dashes? or a digit? or is it what is blinking the D and R?
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Old 09-28-2020, 11:30 PM   #3
Bus Nut
Join Date: May 2015
Location: Miami, Fl.
Posts: 280
Year: 1999
Chassis: Amtran / International
Engine: DT466E-Md3060
Here is a link for the Allison WTEC 3 troubleshooting manual.

Warning, it is 436 pages!!

Also, here is a link to a thread from an RV forum that talks about the same problem and it has a solution to his problem. Looks at posts 5 & 6.

Hope you can find what you need...
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Old 09-29-2020, 12:52 PM   #4
Bus Nut
Join Date: May 2015
Location: Miami, Fl.
Posts: 280
Year: 1999
Chassis: Amtran / International
Engine: DT466E-Md3060
Here is some more info from another forum.
This guy found his problem with bad wiring at the connectors for the tranny.

I had a very similar situation with my bus, corroded wire inside the actual connector. I only found out because out of desperation I started unplugging and re-plugging just to check and hopefully get lucky...I did get lucky!

See post #2 in my thread -

you'll see pictures of what I found on my bus.
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