Allison down shift

[Murray the Cop]

I have had shift problems with my truck since day one. I now have a Suncoast 5 and still had the problems after the install. I just had two computers programmed at the dealer, ECM & TCM. Seems that the delayed shift is pretty much gone. Now a new problem has arisen. It came up before the comp change. The down shifts when slowing are very harsh. The harder I stop the worse they get. On a real hard stop the down shift will actually activate the anti lock brakes and the next stop, if gradual, will be fine.. Any ideas.

[madmatt]

Any codes? Whats your ECT read when it does this.

[Jim Brzozowski]

Might be because of the TC stays locked up and doesn't coushion the gear change. Does anybody know it the ecm accelerates the engine to the proper RPM before engaging the clutches in the trans. on a stock downshift? Sounds like a pretty harsh condition. Assuming you are in tow haul mode when this happens, right?