Allison Trouble

PCAB · September 17, 2001

Has anyone had problems with their Allsion 5 spd? My check engine light came on this morning and wouldn't go out, plus the tranny wouldn't shift. Had to keep shutting it off and back on to get it to shift.Took it right in (limped in rather) and the dealer did a quick scan and said a pressure control valve is stuck. Just curious if this problem has surfaced with anyone else.

Stepside Z · September 17, 2001

I have heard of some problems with the Allisons but they all seems to be computer related. Good luck with it.

Jpshostr · September 18, 2001

I have heard of a few computer related programming problems in the very first Allisons. Seemed like they fixed the problem since I haven't heard much of it since. The symptoms sounded like what you are going through, so hopefully it should be an easy fix.

PCAB · September 18, 2001

The Dealer downloaded a tranny trouble code of P0700. They cleared the code and it would not come back. Might have been just a glitch. Drove home fine and no warning lights this time. Overall, though I am very impressed with this Allison tranny.

Kansas Kid · September 18, 2001

I hope that is just a one time problem. The Allisons have had several problems this first year in the HD trucks, mainly fluid leaks and electronic problems like what you described. Most annoying problem seems to be the aggresive shifting out of OD when pulling with the cruise control on, more so with the Duramax.

I agree that the Allison is the best HD automatic available right now, and alot of people like it. I'm not one though, after driving the ZF 6-speed there is no comparison..

lyonsd · September 24, 2001

What are the gear ratios in the Allison?

Kansas Kid · September 24, 2001

Quote from PCAB, posted on Sep. 18 2001,4:16

The Dealer downloaded a tranny trouble code of P0700. They cleared the code and it would not come back. Might have been just a glitch. Drove home fine and no warning lights this time. Overall, though I am very impressed with this Allison tranny.

The PO700 is there to tell the tecnician that the TCM (transmission control module) has logged a code (or codes)..

That is from an Allison technician. I don't think you have anything to worry about, just probably a brief computer glitch. Hopefully it won't come back.