21-011-16

Flash: Transmission Diagnostic And Shift Enhancements This bulletin involves reprogramming the Transmission Control Module (TCM) with the latest available software. Some customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation, a technician may find the following Diagnostic Trouble Code (DTC) stored in the TCM memory: · U0404 - Invalid Data Received From Gear Shift Control Module "A". In addition, customers may experience the following conditions: · Bumps on 2 - 1 down-shift while braking. · The M on the shifter and Instrument cluster may be blinking. The following improvements are included in this update: · **Improved 2 - 1, 3 - 2 and 6 - 5 down-shifts (6.4L only).** · Improved 1 - 2 light throttle up-shifts.