Need some Help

[MountainMan4]

Hi. My wife and I just bought a 1998 Newmar Mountain Aire with the 8.3 Cummins and Allison Trans. On acceleration, it sometimes seems to hesitate when shifting and when I brake, the trans downshifts hard sometimes. Is this condition normal or what? Also, the dash light indicator for the trans stays on sometimes for several minutes after I start it up and then goes out. I am unable to shift into drive or reverse until this light goes out. The shifting problem seems to get "better" - meaning that it shifts smoother and doesn't downshift hard after the trans warms up. Any input would be greatly appreciated. Wade and Lori.

[Steve Ownby]

Do you have any maintenance records indicating when the transmission was serviced last? Allisons are almost bulletproof but keeping the fluid & filters changed on schedule is very important. The fluid and/or filters may be dirty.

Steve O

[GaryKD]

Hi Wade,
I agree with Steve. Change the fluid and filters and see what happens. It is the first (and maybe only) cheap and easy step to solving this problem. Make sure you install the recommended fluid and filters. Most of us are using Transynd fluid.

[MountainMan4]

Supposedly, the trans was serviced when we picked it up. The fluid is nice and red and doesn't smelled burnt.

[MountainMan4]

We are due to take it back to the RV dealer where we bought it in a couple of weeks to have a hitch put on it and have our Yukon rigged up for flat tow. I have a call in to them now - waiting on them to call me back. Fluid and filters supposed to have been changed when we picked it up. Will let everyone know how things are going.

[MountainMan4]

UPDATE to this post: My cousin works at Allison and he is sending the info to the engineering dept there for followup!! Good ole cuz. Also to check (he says) are the connections to the transmission - reason - the negotiations with the sensors upon startup is taking longer than normal (this is the reason the trans indicator light stays on sometimes for a long time). And, to follow-up with that, the sensor maybe suspect. There is a diagnostic (a pronostic as Allison calls it) that can be run on the trans to pull codes. I'm going to do that this morning. Good Luck to me.

[Mike Canter]

Did you know that with the tranny fluid warmed up to over 140*f and the motor running and the tranny in neutral you can push push the up and down arrows at the same time on the shifter panel and it will read out any fault codes. It willfirst show you the fluid level then go into fault codes.

[MountainMan4]

Yes. We have a complete owner's guide with the trans booklet. I'm letting the coach back down off the jacks today and going through the codes as the booklet shows. Thanks so much for this reminder. I was supposed to get around to doing it yesterday. Thanks.

[allisontec]

I am wandering if your M/H has an exhaust brake. If so you need to monitor your shift pad to see what gear it selects as soon as you let off the throttle.This is your preselect position.Some older coaches were factory set to 2nd gear,this can be changed by your local Allison Distributer,most motor homes like to be set for fourth gear as this is your direct drive (not overdrive) and will hold back better. Being set for second will result in a very aggresive downshift pattern(this is normaly used for much heavier vehicles)If you have a red check trans light then you should have a code stored in your computer.

[MountainMan4]

Yes. The M/H has a red shift light indicator and it does have an exhaust brake. When I activate the exhaust brake, it does show 4th on the shift indicator. When I lift from the throttle, I have noticed that it sometimes stays in 6th. We just got back from a short trip and now am finally getting able to do a diagnostic using the shift indicator.

[jimhfurlong]

How do you do the diagnostic on the Allison 6 speed? Any help would be appreciated!

[Mike Canter]

You push both the up and down arrows at the same time and it will first check the fluid level then it will read any codes.

[MountainMan4]

It seems to be doing better. I took it back for a complete service and they found a trouble code and cleared it. I've driven it about 1,000 miles since. OK so far. And, BTW, they did change the fluid and filter. I think the trouble code was the trouble.