I was backing a heavy trl into the yard this am in 4 lo when it poped out of gear and gave me the shift range inhibited message....what does this mean....thanks...mike

its probably just the Allison TCM protecting the transmission.

its pretty much impossible to "hurt" the Ally by driver error...meaning if you are going 10mph in reverse and slam it into drive, the TCM will not allow the range-to-range shift to protect the trans. No fun neutral drops possible! ):h

The only way to hurt it (I think) is to slam it in park when you're moving.

when you're in 4LO, the gearing is really low so when you shift between drive and reverse, the gears may actually still be turning when it appears you are stopped. The tranny probably sensed this and prohibited the shift. Maybe check to see if any codes are stored? It should be fine tho....but Id check with Mike to amke sure...

thanks ben...i am hoping it is nuttin to worry about.....do i need to go to someone with a tech 2 to check for stored codes?

in the TCM, yes, only a Tech 2 can read TCM codes.

I was backing a heavy trl into the yard this am in 4 lo when it poped out of gear and gave me the shift range inhibited message....what does this mean....thanks...mike

This is normal, its just a protection mode, to prevent you from shifting forward/reverse, etc when the transmission is still moving.

This is why people who plow snow hate the allison, because when you get stuck in a snowpile, you cannot "rock" the truck to get it unstuck. I got a plow truck (8100 V8, Allison Auto) stuck a few times, and the minute you try to rock the truck, you get that message, along with a long delay in shifting gears.

id rather have the Ally be smart like that tho...ive been careless with range-to-range shifting on other automatics and was greeted with a lovely grinding gears noise :)

Quadzilla programer will read TCM codes also.

ahh I forgot about that...although from what ive heard, the Quad will only "sometimes" read TCM codes, and is kind of hit or miss if it reads all the codes. Same thing with PPE that claims their tuner has the "trans reset" function.