Flash: Transmission Control Module (TCM) Updates Customers must experience a Malfunction Indicator Lamp...

Bulletin number

21-028-26 REV. A

Component

Power train

Summary

Flash: Transmission Control Module (TCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0826-00 - Up/Down Shift Switch. ● P0827-00 - Up/down Shift Switch Circuit Low. ● P085F-00 - Up And Down Shift Switch Circuit Range/performance. Customers may also experience one or more of the following: ● Customer is unable to switch the ignition to OFF when in Park gear. ● After shifting into Park, the Instrument Panel Cluster (IPC) will display that the transmission is in Neutral. NOTE: The transmission will actually be in Park and able to hold the vehicle, but the cluster display would indicate Neutral, preventing the engine from shutting off. ● Rough/bumpy 2-3 power on upshifts and/or 3-2 coast down shifts. ● Vehicle enters into limp home mode. Other software improvements: ● Decreased sensitivity to DTCs P1D8A and P1D8B. This bulletin involves inspecting and if required reprogramming the TCM with the latest available software

Owners of these vehicles have filed 16 complaints in the transmission category.