21-007-20

Flash: Transmission Control Module (TCM) Updates This bulletin involves reprogramming the TCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following Diagnostic trouble Codes (DTCs) have been set:P0731-00 - Gear 1 Shift Incorrect Ratio. P0733-00 - Gear 3 Shift Incorrect Ratio (while operating in 4-Lo range). P0734-00 - Gear 4 Shift Incorrect Ratio. The customer may describe the following:Bump/clunk felt during 1-2, 2-3, 4-5 or 5-6 upshifts. The following enhancement is also included in this software update:Improvements in prematurely setting the following DTCs: P0731, P0733, P0734. Improved 1-2, 2-3, 4-5 or 5-6 upshifts to eliminate bump/clunk felt during these upshifts.