I have a 2001 Chevy 2500HD with the 8.1 and the Allison. For the past few months my truck continues to throw a P1710 & P1711 code at me. It only would throw the code after the trans was warmed up after driving 35-45 minutes. I shut the truck off, and when I go back to start it, all of the gauges jump all over the place and the PRND123 does not light up. I could clear the code or sit for 2-3 minutes, and it is back to normal. The trans gauge has always read under 200 degrees.

I changed both filters, the fluid, and the NSBU switch, and presto the same code continues to come right back.

Of course the local stealership was 100% baffled and really couldn't offer much advice besides replacing the entire valve body.

I ended up replacing the tranny with a much newer unit, from the same year truck just with 80K less miles, as well as a new torque converter. I have 200 miles or so on the new tranny, and now I am throwing the same code almost every time I shut my truck off.

Sorry for the novel, but I wanted to make sure I included everything.

Is it possible that my TCM has gone bad? The tranny shifts are firm and very responsive, it is not over heating, and there are no unusual noises.

I am now completely lost and confused…

It's possible. If you do I have used one.

No used one yet, but I know I can find one. I also found a TSB that might take care of the problem:

#02-07-30-020: Harsh or Delayed 2-1 Downshift, Neutral Feel at a Stop, Shift Busyness, DTCs P0708, P0847, P0872, P0875, P1711, P1713 (Reprogram TCM) - (Apr 22, 2002) Document ID: 880188

You should also check your wiring. Check at the connectors that no pins are backed out and that the wiring is not rubbing through somewhere.