Service bulletin 21-045-25

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
Type	Service bulletin
NHTSA id	11025503
Published by NHTSA	2025-11-13
Manufacturer's number	21-045-25
Manufacturer's date	2025-11-08
NHTSA component	POWER TRAIN

NHTSA's 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. The customer may describe 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. In addition, the following software enhancement is available: ● Decreased sensitivity to DTCs P1D8A and P1D8 This bulletin involves reprogramming the TCM with the latest available software.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Transmission and driveline

Trouble codes named

P0826, P0827, P085F, P1D8A

Vehicles listed
RAM 4500	2026
RAM 5500	2026

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
08-302-26	2026-08-06. Service bulletin. Flash: Electronic Shift Module (ESM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must SYMPTOM: exhibit/set the following Diagnostic Trouble Code (DTC): ● U1057-00 - High Speed Fd-Can3 Communication Bus Performance. Customers may also comment on the following: ● If the vehicle has a low or drained battery and requires a jump start, once jump started, the vehicle will not shift out of Park. This bulletin involves reprogramming the ESM with the latest available software.
S2523000088 REV.B	2026-07-18. Service bulletin. Vehicle Shifter Will Not Shift Out Of Park.
18-002-26 REV. B	2026-07-02. Service bulletin. Flash: Powertrain Control Module (PCM) Updates Customers may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P219A - Bank 1 Air-Fuel Ratio Imbalance Bank 1. ● P219B - Bank 2 Air-fuel Ratio Imbalance. NOTE: This revision has an updated and more effective fix for DTC P219B than the prior version. Customers may also comment on one or more of the following: ● Power Take-Off (PTO) may cancel during engagement with high PTO loads. ● PTO not auto-resuming after hard-wired remote start (DD/DP Only). ● Engine speed surging, unstable, or oscillating while coasting at low vehicle speeds. ● Stationary Idle PTO feature is not activating when the user configuration is selected to require parking brake be set (DD/DP Only). In addition, the following software enhancement(s) is available: ● Increase the duration that Power Takeoff related messages are displayed on the Instrument Panel Cluster (IPC) (DD/DP Only) This bulletin involves inspecting and possibly reprogramming the PCM with the latest available software.
21-029-26 REV. A	2026-05-06. Service bulletin. 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
S2609000005	2026-04-01. Service bulletin. Check Engine Light (CEL) Illuminated Diagnostic Trouble Code (DTC) P0381-00 Wait to Start Lamp Inoperative
S2621000002	2026-03-05. Service bulletin. The customer concern is Service Transmission, preventing the engine from shutting off. 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
21-017-26	2026-03-05. Service bulletin. Flash: Transmission Control Module (TCM) Updates Customers may comment on the following: SYMPTOM: ● Hesitation or delay when accelerating. Customer may state that this occurs when driving at speeds between 5 kph (5 mph) and 20 kph (12 mph) after having previously accelerated from a very low speed and having backed off of the accelerator pedal for a short time. This bulletin involves reprogramming the TCM with the latest available software.
21-012-26	2026-02-04. Service bulletin. Flash: Transmission Control Module (TCM) Updates 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. This bulletin involves inspecting and possibly reprogramming the TCM with the latest available software.
18-002-26	2026-01-21. Service bulletin. Flash: Powertrain Control Module (PCM) 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): ● P0420 - Catalyst System Efficiency Below Threshold Bank 1. ● P0430 - Catalyst System Efficiency Below Threshold Bank 2. Customers may also experience the following: ● Catalyst damage and restricted exhaust flow, resulting in a reduction of engine power. This bulletin involves reprogramming the PCM with the latest available software.
21-006-26	2026-01-14. Service bulletin. 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 reprogramming the TCM with the latest available software.