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Service bulletin D21M1

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)
TypeService bulletin
NHTSA id10191143
Published by NHTSA2021-05-01
Manufacturer's numberD21M1
Manufacturer's date2021-04-19
NHTSA componentPOWER TRAIN

NHTSA's summary

Detroit Field Service Campaign for DT12 Transmission Drive Shaft Cover Plug Reseal. Daimler Trucks North America LLC, on behalf of its DETROIT Powertrain Division, is initiating Field Service Campaign D21M1 on certain DT12 transmissions in order to reseal the bypass plugs of the drive shaft cover located in front housing.

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

Vehicles listed
FREIGHTLINER CASCADIA2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022
WESTERN STAR 49002012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022
WESTERN STAR 49X2021
WESTERN STAR 57002015, 2016, 2017, 2018, 2019, 2020, 2021, 2022

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

Recalls for the same vehicles and component
20211742021-03-24. Powertrain
21V2090002021-03-24. POWER TRAIN:CLUTCH ASSEMBLY
20V7420002020-11-30. POWER TRAIN:CLUTCH ASSEMBLY
20204882020-10-16. Powertrain
20V6420002020-10-16. POWER TRAIN:CLUTCH ASSEMBLY
19V1370002019-02-27. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; POWER TRAIN:AUTOMATIC TRANSMISSION:GEAR POSITION INDICATION (PRNDL)
20187142018-12-19. Powertrain
18V9030002018-12-19. POWER TRAIN:CLUTCH ASSEMBLY
20175692017-11-20. Powertrain
17V7300002017-11-17. POWER TRAIN:AUTOMATIC TRANSMISSION

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
MAN 00000728682026-10-05. Other. Detroit Transmissions Manual Update for Symptom Diagnostics — DT12 C/D Box Range Shift to Neutral with Reversing Events (Aborts)
TSB-42-080-FTL2026-08-03. Service bulletin. Revised Technical Service Bulletin for ABS Wheel Speed Fault Code Correction for MBSP Equipped Vehicles. Updated frequently asked questions.
TSB-26-057-FTL2026-06-01. Service bulletin. Revised Technical Service Bulletin for DT12 OVX Transmission Refresh
TSB-26-001-DDC2026-05-02. Service bulletin. Revised Technical Service Bulletin for DT12 Range Detent Diagnostic
ICI26-0062026-05-02. Other. Important Campaign Information for SF706 - Revised, Reactivated
SF706-DLR LTR2026-05-02. Service bulletin. Revised Field Service campaign for Cascadia Axle Conversion: Adaptive Tandem (AT) 6x4 to New Final Drive (NFD)
SF706-Bulletin2026-05-02. Service bulletin. Revised Field Service campaign for Cascadia Axle Conversion: Adaptive Tandem (AT) 6x4 to New Final Drive (NFD)
TSB-26-001-DDC2026-04-02. Other. Technical Service Bulletin for DT12 Range Detent Diagnostic
ICI26-0032026-04-02. Other. Important Campaign Information letter for SF706 - campaign suspended
FleetCom_SF7062026-03-04. Other. Fleet Communications for SF706 - Cascadia axle conversion