Hi , New member here. Can anyone tell me how to disconnect the downshift feature. I don,t like the way it down shifts and over revs the engine.
Thanks Jerry
04 LB7 / Allison

If by saying the "downshift feature" you are asking about grade-braking, then I don't believe there's any way you can 'disconnect' it. That is one of the major features of the Allison transmission in your truck. It is active in both regular and tow/haul mode, but is VERY much more pronounced in tow/haul. Without tow/haul engaged, it does occur, but is usually not very noticeable, if you notice it at all. It's possible you are driving in tow/haul mode and could just turn tow/haul off to get the results you are looking for. As far as when it "over revs" the engine, don't worry about it. It isn't truly over-revving the engine, just using a feature of the Duramax/Allison combo. Your tach has a dotted red area that engine RPMs may go into when grade-braking occurs, with the solid red line at the very top of the tach being the actual range that's your rev limit. If the grade-braking downshifts were about to truly "over rev" the engine, the programming would force an upshift to avoid engine damage. The Allison takes a bit of time to get used to (I know it felt weird to me at first), but once you have towed with it a few times, you'll really appreciate the merits of the design.

Amen to bluenotes post, you will learn to love the Ally, http://www.dieselplace.com/forum/smileys/Clap.gif especially trailer towing in the hills.

Good answer bluenote.


mike

Or, if you still cant get used to it, you can trade it in for a 6.0 gasserhttp://www.dieselplace.com/forum/smileys/Dead.gif

Search this site. Tons of info. You will soon get comfortable with the RPM’s up to 4800 while grade braking, as it was designed to do. Save your brakes and drive safer.
Here’s a couple of the many, links below:

http://dieselplace.com/forum/forum_posts.asp?TID=156&KW=grade+braking

http://dieselplace.com/forum/forum_posts.asp?TID=13714&KW=grade+braking

I tow a 13K 5th wheel, and would not be without the "smart" features of the Allison.


I too, when the truck was new, had the bejeebers scared out of me when I was coming down the Siskyou Pass into Oregon. I thought that the engine was going to jump out of the truck.


What I have learned is that what scared me was the "fan noise", and not the engine. When the fan is ON it is loud. However, I have many times had the Ally downshift without the fan. All I heard was the purring of the engine. I was smooth and sweat.


Sit back, get used to it, and enjoy it. It will save your service brakes.


Happy trucking.


Lye