Allison Transmission Problem

[Aggiehusky14]

I have a 93 Legacy 34ft diesel pusher with a cumming and a allison transmission. I went out to start it a few days ago and when I turn the key it would not start and the light on the transmission that should show N was not on. I checked the batteries and they were good so I cleaned all the connections by this time it was the middle on the afternoon and it had warmed up and then for no reason when I turned the key on the light came on the transmission and it started and worked fine. Today I went to start it and the same thing happened. I played with the key on and off several times the light blinked and the motor started but no light on the tranny so I let it run and warm up for about 15 minutes and then turned it off.I turned the key and it started just like it should. I don't think the problem has anything to do with the key. Does anyone have any ideals what may be the problem? Should it have something to do with the colder weather, this is florida but it has been about 30 degress here. I know this shouldn't make any difference .

[Guido]

Neutral safety switch, or whatever passes for one on an Allison transmission.

[woodenicol]

It sounds like the neutral safety switch. I had one go on a 2002 allison transmission. I didn't have trouble starting, but I could only use one gear. The next time it would be fine, and the next time I might not be able to move. Turning off the vehicle would sometimes reset it. I wasn't very long getting it in for the repair. I think the switch was around $100.00.

[Paul Dobbin]

I also have a 1994 diesel pusher and have had several experiences with this transmission.
First thing you need to know is that the shift module (display) is also the screen for the electronic shifter. If prompted, it will give a code for the problem it's having. Call the Allison dealer or the 800# and they'll walk you through it. They'll have you push a few buttons and read them the code that's displayed and the code book will describe the problem.
I got a code book at a big RV rally so I could do it myself on the road.
I'd tell you what to do, but the booklet is in the coach a long way from here. That computer module had to be replaced in mine and the part was $2300. I told them NASA could get to the moon with a $500 computer
so the $2300 was ridiculous. They said I couldn't go camping in Space Ship.
Anyway talk to the Allison 800# when you are sitting at the shift module and they'll be of great help is figuring out what's going on an advise you
what to do to correct it or reprogram it.

[blkmagikca]

Allison also has a video tape (VHS) on how to use their transmissions. It was for later models, but the part about doing diagnostics still holds. I had used a Pyro A-V Link to convert it to a .wmv file. This file can be downloaded and viewed. The URL is: http://www.vsquare.com/howard/Alliso...sion_Guide.wmv

(Note I've started the upload, but it may take some time until this file is available - it is 219K in size.)

[ROBERT CROSS]

Next time it happens, try starting in neutral instead of park, move shifter slightly while holding key in start mode. NSS is the most likely cause, but have also had the Ign. switch or instrument panel cluster,(IPC), cause the same symptom.

[blkmagikca]

Originally Posted by ROBERT CROSS

Next time it happens, try starting in neutral instead of park, move shifter slightly while holding key in start mode. NSS is the most likely cause, but have also had the Ign. switch or instrument panel cluster,(IPC), cause the same symptom.

Bob, if his diesel pusher is like mine ('94 LY), it has air over hydraulic brakes. As such, there is no "park" position for the transmission. Instead, there is a maxi-brake, which requires air pressure to release the rear drum brakes (absent the air pressure, there is a powerful spring which applies the brakes). As well, my '94LY does not have a shift lever - rather it has a push-button pad.

Howard

[ROBERT CROSS]

Originally Posted by blkmagikca

Bob, if his diesel pusher is like mine ('94 LY), it has air over hydraulic brakes. As such, there is no "park" position for the transmission. Instead, there is a maxi-brake, which requires air pressure to release the rear drum brakes (absent the air pressure, there is a powerful spring which applies the brakes). As well, my '94LY does not have a shift lever - rather it has a push-button pad.

Howard

opps!

[Paul Dobbin]

Just a note of information about the Allison for future reference.
The shift module on the Allison uses lots electricity to shift. The
alternator alone does not provide enough to shift the transmission,
it needs a battery reserve.
Things I've learned:
#1: A diesel will run (but not start) with the batter disconnected
(or dead) and it can die while running.
#2: If you ar driving, it will run on the alternator, but when the
battery is to low it won't shift.
#3: If the alternator fails it will eventually run the battery dead
shifting the coach until there is not enough juice to shift it.
#4 The battery can be so dead when running that the Allison
shifter module can't dianose anything.
#5 The Allison guys can dianose you problem by the codes
displayed on the shift pad when you push both up & down
shift arrows at once.
#6 Allison will share that list of shift codes with you.

[georgelift]

I have the same problem. What was the solution?
thanks,
George

[blkmagikca]

After a 3 month stay in Casa Grande AZ, I pulled out onto I10 to head to Florida. Within a few miles I started to have some troubles with the transmission - it would kick into Neutral. I managed to baby it into Tucson and into Beaudry RV. I figured it was a major job. It turned out that the connections to the main ignition solenoid located in the front storage (diesels have a rear engine) were loose. The error code I was getting translated into "no communication", meaning that the touch pad and the transmission were not in communication.

Vibration is a major headache and cause of many of the ailments of motorhomes, particularly the electrical connections at the beaker panel. Check them out from time to time.

Another issue is torquing the wheel nuts. On my LY they have to be torqued at 450 foot-lbs. Very few garages or tire shops have such a torque wrench. The answer is to get one yourself - it can save you a major problem if your wheel nuts loosen. I had tried to get one at Harbor Freight, but they were out of stock. I did find a really good one made by Precision Instruments at toolwarehouse.com - it has a split beam and does not require resetting to zero each time you use it.

[Stillers6pac]

We had this same problem with our 94 Legacy D/P.Somehow temp has direct effect with the Shift-Module Display.(1)Occurs in colder temps,less than 50degrees.(2)Warming the"SMD"box will allow it to operate normally.This was revealed as Iwas trblshting with a worklight..(3)Reoccurs after cooling down.Has anyone else seen this? Please offer any experience & or shared knowledge. The key thing here is without the 2 "NN"s on the keypad display,one cannot select anything withy trans..(until the box is warmed-up).