Here is where its at so HPTuners can add the missing D1 tables to the editor definitions. Standard two byte speed values (Integer/256 = mph), Standard 17 element table (vs TPS). Location is between the last of the shift speed tables but before the beginning of tcc speed tables. In the 2002 12212156 OS the table starts 4502 bytes into the transmission segment. For the 4L80e calibrations it functions as the "upshift vs tps for D1 shifter selection". I have tested it on the 2002 12212156 and 2004 12587603 OSs. There are 3 more tables right after it. I'm pretty sure the next 34 bytes are "downshift vs tps for D1 shifter selection" but I have done no testing to verify as they are all already set to 255mph on every calibrations I've looked at. It was easy to find because I knew I was looking for 22 or 23 mph from what I'd seen in the logs. All stock 80e calibrations Ive seen are 22.5mph up to 50% tps and 255mph from there on up. Set the whole table to 255mph and D1 functions as you would expect, letting you hold 1st gear until the shifter is moved out of D1. Now the values I've seen in these locations on 4L60E calibrations would still make D1 upshift early (which they don't), so there must also be a switch that controls if the ecm uses these tables or not. Reguardless having access to these tables on 80e calibrations that work that way solves the problem. The tables HPtuners currently calls D1 is either just a saftey shift table or the other side of what ever switch controls the use of the table.
This is a must for someone wanting to be able to pedal the gas while doing a burnout, racing from a roll, or more importantly for those using a Jakes's performance trans brake where an unwanted 1>2 shift while D1 is selected will enable the brake and potentially destroy the transmission.
I'm sure Chris can take it from here....