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October 18, 2025 Service bulletin

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

Ram technical service bulletin 21-027-25 REV. B for 2025 Ram 2500.

Bulletin number
21-027-25 REV. B
Component
Power train
Summary
Flash: Transmission Control Module (TCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0827-00 - Up and Down Shift Switch Circuit Low. ● P0826-00 - Up and Down Shift Switch Circuit. ● P085F-00 - Up and Down Shift Switch Circuit Range/Performance. ● P1DCD-00 - TCM Monitoring Processor Performance Multiple Clutches Locked Up. Customers may also experience one or more of the following: ● Vehicle stuck in default gear, and possibly stranded for many minutes. ● Rough or 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 possibly reprogramming the TCM with the latest available software.

Owners of these vehicles have filed 8 complaints in the transmission category.

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