WARNING: This page is about a different car, the 1994 Cadillac Fleetwood. However, it is still accessible from the selected car via links, so may be relevant.
If TCC is mechanically stuck on, vehicle speed is zero, brakes are applied, and D2 is selected, TCC fluid will mechanically apply the TCC, causing an engine stall.
Fig 1: Code 85 Schematic (Fleetwood) TCC Stuck On
Fig 2: Code 85 Flow Chart (Fleetwood) TCC Stuck On