Technical Service Bulletin (TSB)
Flash: Transmission Control Module (TCM) Updates
REFERENCE:

TSB: 21-003-26
GROUP: 21 - Transmission and Transfer
Case

Date:

January 8, 2026

VEHICLES
AFFECTED:

2025 (DJ) RAM 2500 Pickup
This bulletin applies to vehicles equipped with the 6.7L I6 Cummins
Turbo Diesel Engine (Sales Code ETM) and an 8-Spd TorqueFlite HD
Auto Trans (Sales Code DFM).

REVISION: 21-027-25 REV. B

MARKET APPLICABILITY:
NA

MEA

SA

IAP

EE

CH

NOTE: This bulletin applies
to the North America
market.
CUSTOMER
SYMPTOM:

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.

CAUSE:

TCM software

This bulletin supersedes Technical Service Bulletin (TSB) 21-027-25 REV. B, date of issue October 18,
2025, which should be removed from your files. All revisions are highlighted with **asterisks** and
include updated Customer Symptoms, a new Customer Symptom Note and a new LOP.
**This Technical Service Bulletin (TSB) has also been released as a Rapid Service Update (RSU)
25-052, date of issue April 02, 2025. All applicable RSU VINs have been loaded. To verify this RSU
service action is applicable to the vehicle, use VIP or perform a VIN search in DealerCONNECT/Service
Library. All repairs are reimbursable within the provisions of warranty.**
REPAIR SUMMARY:
This bulletin involves inspecting and possibly reprogramming the TCM with the latest available software.

J21 FSAR-TSB-6798

-2-

CLAIMS DATA:

Labor Operation No:
**18-19-05-TD

18-19-05-TE

Failure Code

Labor Description
Module, Transmission
Control (TCM) - Inspect
Software Level
(0 - Introduction)
Module, Transmission
Control (TCM) - Inspect
and Reprogram
(0 - Introduction)
RF
CC

Skill Category
2 - Automatic
Transmission

Labor Time
0.2 Hrs.

2 - Automatic
Transmission

0.3 Hrs.**

Required Flash - RSU
Customer Concern

The dealer must choose which failure code to use depending on if this is a Rapid Service Update
(RSU) or Technical Service Bulletin.
● The “RF” failure code is required for essential module flash/reprogramming and can only be used after
confirmation that the VIN is included on the RSU.
● The failure code “RF” (Required Flash) can no longer be used on Technical Service Bulletin flashes. The
“RF” failure code must be used on an RSU.
● If the customer’s concern matches the SYMPTOM/CONDITION identified in the Technical Service Bulletin,
failure code CC is to be used. When utilizing this failure code, the 3C’s must be supplied.
DIAGNOSIS:
Using a Scan Tool (wiTECH) with the appropriate Diagnostic Procedures available in DealerCONNECT/
Service Library, verify all related systems are functioning as designed. If DTCs or symptom conditions, other
than the ones listed above are present, record the issues on the repair order and repair as necessary before
proceeding further with this bulletin.
If the customer describes any of the symptoms listed above in the customer symptom section, perform the
Repair Procedure.
SPECIAL TOOLS/EQUIPMENT:

Description
wiTECH or Equivalent

Ref. No.
–

Notes
–

REPAIR PROCEDURE:
NOTE: Install a battery charger to ensure battery voltage does not drop below 13.2 volts. Do not allow
the charging voltage to climb above 13.5 volts during the flash process.
NOTE: If this flash process is interrupted/aborted, the flash should be restarted.
1. Is the vehicle on the RSU VIN list?
● YES >>> Proceed to Step 2.
● NO >>> Proceed to Step 3.

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J21 FSAR-TSB-6798

2. Does the TCM have the latest software already installed?
● YES >>> This bulletin has been completed, use Inspect LOP **(18-19-05-TD)** to close the active RSU.
● NO >>> Proceed to Step 3.
3. Reprogram the TCM with the latest software. If any issues arise when flashing a module using the wiTECH
Diagnostic Application, please submit a ticket to the Helpdesk. The helpdesk can be found within the Help
menu.
4. Clear any DTCs that may have been set in any modules due to reprogramming. The wiTECH application
will automatically present all DTCs after the flash and allow them to be cleared.
POLICY:
Reimbursable within the provisions of the warranty.
This bulletin is supplied as technical information only and is not an authorization for repair. No part of this publication may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise, without written permission of FCA US LLC.