You mentioned that you had unhooked the battery and that the car is in limp mode. Was browsing through the service manual and found the following. May or may not have some relevance.


BATTERY FEED
A fused, direct battery feed to the Transmission Control Module is used for continuous power. This battery voltage
is necessary to retain adaptive learn values in the Transmission Control Module’s RAM (Random Access Memory).
When the battery (B+) is disconnected, this memory is lost. When the battery (B+) is restored, this memory loss is
detected by the Transmission Control Module and a Diagnostic Trouble Code (DTC) is set.
LIMP-HOME MODE
In order to ensure safe driving and to prevent further damage to the automatic transmission, the Transmission Control
Module switches to limp-home mode in the event of a critical failure. A diagnostic trouble code assigned to the
failure is stored in memory. All solenoid and regulating valves are thus de-energized. The result is that the gear last
engaged remains engaged, the modulating pressure and shift pressure rise to the maximum levels, and the torque
converter lockup clutch is disarmed. In order to preserve the operability of the vehicle to some extent, the automatic
transmission internal hydraulic control can be used to engage second gear or reverse by: stopping the vehicle,
switching off the engine, moving the shift selector lever to Park, waiting at least ten seconds, starting the engine,
and moving the shift selector lever to drive to access second gear, or moving the shift selector lever to Reverse if
needed. The limp-home function remains active until the failure is corrected or the stored diagnostic trouble code is
erased. Sporadic failures may also be reset by switching the ignition switch from Off to On.
Note: If the TCM has been replaced, the “TCM Quick Learn” procedure must be performed.
STANDARD PROCEDURE - TCM QUICK LEARN
The quick learn procedure requires the use of the DRB IIIT scan tool.
This program allows the electronic transmission system to recalibrate itself. This will provide the proper transmission
operation. The quick learn procedure should be performed if any of the following procedures are performed:
² Transmission Assembly Replacement
² Transmission Control Module Replacement
² Solenoid Pack Replacement
² Clutch Plate and/or Seal Replacement
² Valve Body Replacement or Recondition
To perform the Quick Learn Procedure, the following conditions must be met:
² The brakes must be applied
² The engine speed must be above 500 rpm
² The shift lever position must stay in Park until prompted to shift to Drive
² The shift lever position must stay in Drive after the Shift to Drive prompt until the DRBIIIT indicates the
procedure is complete
² The calculated oil temperature must be above 60° and below 200°