2wd to 4wd 2004 5.3 L59 OS 12587603

[BagD72Chevy]

I'm helping a friend with a Jeep conversion and I am in completely new territory. 19 LS conversions and I have never messed with anything 4wd. Figured it is time to learn. I helped with another one but the VSS was in the tcase adapter, so no 4Lo problems. Specs:

2004 L59 5.3 2wd Engine and Trans. Trans was rebuilt with a 4wd output shaft. A NP241c manual shift transfer case was swapped in from a 1995 Z71. It has a 40 tooth reluctor and a shift switch. I wired the 4lo switch into C2-16 (4wd Lo Signal). I made the entire harness myself with Auto grade txl wire (All oem colors) and brand new delphi connectors. I changed the cal in original pcm supplied not thinking about the 4wd issue.

Problem I ran into today. It runs great in 2Hi and 4Hi. In 4Lo it still uses the vss shift tables as if it were in high range. I have a 4x4 tune file from a Tahoe with the same OS as is currently have on the pcm. Looking through it I do not see any transfer case settings. Have these not been defined/mapped yet? Im hoping this file will solve my issue but I am also curious about changing the 4Lo gear ratio as my personal build has an Atlas case with 4:1 lo range.

My plan is to get my calibration changes put into the 4x4 file and flash onto the pcm. Then test the 4Lo switch by monitoring with my Tech2. If that works test drive. Hoping for the best.

Thanks for any insight and help on the issue.

[BagD72Chevy]

So....The wiring diagram I had for the transfer case switch was incorrect. I pinned out the conenctor on the tcase in all positions with my Fluke and figured out one wire was ground, the other was 4wd, the last low range. Wired it up correctly with a 4wd tune file and the Tech 2 still doesn't register the state change in Transmission Data. But a test drive proves it works fine. If I get a chance I want to flash the 2wd tune file back on and see what happens. Is it really missing that part of the calibration or not??

Thanks,
Ryan