Severe Problems with AW30-40 Transmission - '96 960

[YTJOHN]

Transmission in my 1996 960 was operating fine until the arrow warning light and winter/sport/economy switches starting flashing after a 10 mile drive. Drove it another mile to my house and it lost drive and reverse entirely. Let it sit for 10 minutes and was able to drive the car into its parking spot. Fluid looked clean, so I took it to a shop that could read the diagnostic codes. Codes were:
AT-232 - speed sensor absent
AT-114 - mode selector switch signal
AT-341 - lock-up function slipping
They suggested I troubleshoot the circuits involved in sending the speed signal to the transmission. So I first checked the harness connectors underneath the transmission and near the dipstick area. Test drove car and had same symptoms: severe slippage on a hill, but able to move after 10-15 minute shutdown. Since the speedometer works during these "breakdowns," I figure the speed sensor in the rear axle is working. I removed the instrument cluster and checked continuity from the speedo to the transmission control module. Also, from TCM to ground. Swapped the transmission control module with another one. Car continues to drive OK for a few miles before severe slipping reoccurs.
This transmission had fluid flushed and replaced with synthetic less than 6 months/3,000 miles ago. Less than 150K total, documented miles on it.
Interested in anyone's experience with these codes and/or problems.
Have a happy 4th!