I'm a hobby programmer and have written a windows program for the Jeep KJ 3.7 in the last 12 months.
This program shows the status of a 42RLE transmission. After a few test drives it seems to work well.
I have uploaded a video to YouTube which is showing such a test drive.
The program runs on a laptop with bluetooth and is using an ELM327 bluetooth adapter.
YouTube link: http://youtu.be/8ZrLmeXtnvs
If you have an ELM327 bluetooth adapter you can also download a test version of my program from here.
A friend told me that the Jeep TJ has a PCI bus and a 42RLE transmission (2003-2006) too
so the software may also run on this Jeep type.
But I'm not sure because I can not test it.