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Default Desensitization




As of April 1996, a new TCM calibration has been released for vehicles built starting in mid-February and is being made available to flash update previous 1996 model year 41TE/AE. This new calibration reduces the tendency for the transmission to go into the limp-in mode (2nd gear only in OD, 3 or L, PRNO3L positions) for the following intermittent DTC conditions:
- 15 Transmission Relay output always OFF
- 22 2-4 Pressure Switch sense circuit
- 50 Gear ratio error in reverse
- 51 Gear ratio error in first
- 52 Gear ratio error in second
- 53 Gear ratio error in third
- 54 Gear ratio error in fourth
- 56 Input Speed Sensor error
- 57 Output Speed Sensor error
- 58 Speed Sensor ground error

Previous calibrations result in an immediate limp-in mode condition when a DTC is sensed during key ON, and vehicle speed is below 45 mph.

The new calibration always sets a DTC as soon as an electrical, mechanical or hydraulic problem is identified. But the transaxle may not go into the limp-in mode until the problem happens several times in a given key start (DTCs 22,50,51,52,53,54,56,57 or 58) or after several key starts while identifying the DTC in Park or Neutral before vehicle operation begins (DTC 22). If DTC 24 and/or 37 is set, 1st gear and the EMCC will be inhibited and no limp-in mode will occur. In addition this new calibration will eliminate DTCs 23, 25, 26, and 27 which would have been set when trouble with 2 or 3 of the pressure switch circuits existed. The new calibration will set a single fault code for every affected pressure switch circuit instead of one combinational code (23, 25, 26, 27).

After installing this flash update, hard DTCs (DTCs that occur every key start) will still eventually cause a limp-in condition for TCM DTCs (DTCs that occur every key start) 15, 22, 50, 51, 52, 53, 54, 56, 57 and 58, but will take more time and/or key starts than in previous calibrations. Several hard, as well as intermittent hardware related DTCs will be tolerated indefinitely, will not illuminate the MIL, and will not allow limp-in mode operation even though the DTC is set in the TCM as soon as the DTC is sensed (i.e. TCM DTCs 21 and 24).

NOTE: The MDS is required to perform this flash update. The MDS must be operating with release 19, or higher, and Technical Information Library (TIL) CD release 1106, or higher, installed.

Perform the following procedure for the update:
1. Connect the MDS and DRBIII (Scan Tool) to the vehicle and power them up.

NOTE: For the 1996 Model Year and future vehicles, the TCM can be reprogrammed from the diagnostic connector. The flash programming kit (CH5500) is not needed.

2. Use the arrow keys on the DRBIII and from the MAIN MENU screen select MDS DIAGNOSTICS.
3. Use the arrow keys on the MDS and select DIAGNOSTIC MENU from the MDS screen, then press NEXT MENU.
4. Use the arrow keys on the MDS and select VEHICLE CONTROLLER PROGRAMMING, then press NEXT MENU.
5. Use the arrow keys and select PROGRAMMING OF ALL OTHER CONTROLLERS WITH MDS & DRBIII on the MDS, then press NEXT MENU.
6. Follow the steps presented on the MDS and DRBIII, which will allow the DRBIII to obtain the current part number of the PCM.
7. The MDS will display the description of the updatable PCM and/or TCM on the vehicle and the appropriate replacement part number(s). Select the description of the TCM, then press NEXT MENU to begin programming.
8. The MDS and DRBIII will prompt for any operator action needed during the remainder of the programming process. If both the PCM and TCM on the vehicle have already been updated, a NO UPDATES AVAILABLE message will be displayed. If this is the case, verify the Authorized Modification Labels attached to the TCM and near the Vehicle Emission Control Information (VECI) label. If the labels are not attached, proceed to step 9. Otherwise, end the procedure.





9. Type the necessary information on the Authorized Modification Label and attach the label near the VECI label.





10. Type the necessary information on the Authorized Software Update Label and attach it to the TCM and cover label with a clear plastic sticker.

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