I just experienced when going down a grade with my 10,000 lb 5er in T/H the tranny shifts down hard to about 3100 RPMS then I give it a little gas and it shifts up hard and kinda seems like I get "turbo bark" in the process. Has anyone else seen similar symptoms ?

FYI I am running Edge/Attitude on level 2.

Are youulling a load when this happens. Mine seems to shift hard becouse it will kinda jerk the truck when i give it gas to up shift. Thats becouse of all the weight im pulling it just feels like a hard shift. no ses light it shoudnt be a problem. Mike L. would know alot more than me. maybe he will chime in later.

Yes I am towing a load when this happens, I haven't seen a SES light yet either.

Is your attitude set to defuel on shifts? This may not be your problem but it might add to the hard shift feeling. Just my .02.

Yes I am set up for defuel on all locked shifts.

This happens to me a lot the best thing to do is to let the truck coast down to a reasonable rpm before u give it gas (2100-2500). Mine shifts real hard a blows out white smoke when i gas it to upshift when the rpms are at 3100( which is the point that the engine quits making usable horsepower in stock trim)

Thanks for the info guys...

This is due to the tranny grade braking feature in the allison, don't know much about it other than when I am towing our 30ft WW and in T/H on a grade under hard breaking the tranny will downshift and hold a gear in an attempt to slow the vehicle and the only way to "cancel" this action is to apply some gas until it shifts back up or cancel T/H mode.