We had a no light/no start issue with out 3000 transmission and in the end they replaced the TCM. Cost was ~$3500, I know there are places that you can send you TCM to for repair for a lot less money but unfortunately I was headed out of country and my wife had a trip planned. Had to have it towed to an Allison shop, they diagnosed the TCM and replaced it.
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi