Allison Shifting Problem

[Ronbstewart]

I have 1994 Monaco Executive with 300 cummins (8.3) and Allison push button automatic (MD 3060) I believe. I live in OH and have owned the coach about a year. Coach has 89000 miles of which I put on 9000. I have noticed recently when the out side temp is around 30 degrees or below the transmission once shifted out of "N" into "D" or "R" will not shift back into "N" until engine has warmed up a bit. Will shift from "D" to "R" or "R" to "D" with no problem when either of those buttons are pushed, but nothing when "N" is pushed until it gets warm. Once warmed up "N" can be selected with no problem. I have no idea where to start with this problem even though I do most of my own work on the coach.

[Mike Canter]

When was the last time the fluid and filters were changed? What fluid is in the transmission?

[bdpreece]

Do you have any service records on when or if the transmission filters and fluid has been changed? If it were me I would invest in a new set of filters and have the fluid drained and transynd fluid installed. I am sure there are transmissions that have failed but for the most part Allison builds an almost bullet proof transmission if it has the recommended services.

[Ronbstewart]

Thanks for your reply and I must admit with some shame I don't know when the last time trans fluid was changed or what brand/type is in it. I purchased the unit by way of an ebay auction in Dallas, flew down picked it up and drove it back to OH. Changed the engine oil and all other filters. Transmission fluid level was full at that time so I haven't bothered with it since.

[a k]

Did you get it thru Recreation Live?

[Mike Canter]

Ron, it is having a problem because either the fluid is thickerning up in the cold and it is not flowing enough. that can be caused by dirty filters and/or old transmisson fluid. I would recommend changing both. Also if you use the Allison Transynd synthetic fluid it is a more constant viscosity in both cold and hot weather for better performance.

[94-Newmar]

Could be the transmission selector pad. The membrane behind the D-N-R buttons get stiff as they age and the contact points behind on the circuit board no longer make good contact. If the keypad is cold it would make them even stiffer. Seems to make sense since it eventually starts working after the keypad has been on for a few minutes as they do generate a bit of their own heat - perhaps enough to soften up the membrane behind the buttons. I honestly feel that if it were a fluid viscosity, flow or fluid level issue that it wouldn't want to select any gear, not just neutral.

Changing your trans fluid and filters is never a bad idea, however I suspect that has nothing to do with your problem you've posted. Along with the buttons not working properly, such as having to push on them real hard or complete failure, many have had problems with the power supply going bad in these older WTEC-II shifter controllers starting at about 15 yrs of age (including me). Might I suggest calling John at Transmission Instruments about taking a look at your keypad. For $300.00 he can rebuild your WTEC-II controller completely - replace the power supply and replace the shift buttons and membrane. When/if the power supply fails you're not going anywhere until it's replaced, I know from 1st hand experience! Allison wants over $2000.00 to upgrade to a newer WTEC controller and Trans control module, John charges around $300.00 to rebuild your controller which is EASY to remove, approximately 15 minutes. Visit his website, lots of pictures, including this one of the VERY common Neutral button wearing out, which is very obvious.

[Mike Canter]

94 Newmar. Would that keyboard membrane cause it to only malfunction if the outside temp was at 30*?

[Ronbstewart]

Thanks again for the good info, I'm going to start with fluid and filters change since I have no idea when either was last changed and if that doesn't solve the problem will have the key pad rebuilt.

[Mike Canter]

Ron, run a diagnostic test on it and see if there are any fault codes. You do this my turning on the ignition and then on the keypad pressing both the UP and the DOWN arrow at the same time twice. The first time you press both arrows at the same time you get the fluid level but the trannsy fluid has to be above 140* or you get a fault code then if you press both the UP and the Down arrows again you read the diagnostic codes. If there is a problem with the keypad then it should drop a fault code.

You can read or download the Operators Manual here and it explains it all and gives you a breakdown of what the codes are
Operators Manual