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Service bulletin DT12 Trans Chafe

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 id10190020
Published by NHTSA2021-04-08
Manufacturer's numberDT12 Trans Chafe
Manufacturer's date2021-03-10
NHTSA componentEQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; POWER TRAIN

NHTSA's summary

DTNA received a field notification on multiple units regarding diagnostic fault codes that were found to be causing issues to the After Treatment Control Module (ACM). These fault codes indicated that the ACM communication message was not received by the Motor Control Module (MCM) which in certain cases, led to a 25% engine de-rate situation. Further diagnosis revealed that the DT12 wiring harness was chafing and contacting the transmission TCU case. To reduce potential chafing areas, the proposed short-term containment was to route the wiring harness using additional tie straps. This communication applies to Freightliner and Western Star vehicles built with DT12 transmissions.

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

Equipment and accessories, Transmission and driveline

Vehicles listed
FREIGHTLINER CASCADIA2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022
WESTERN STAR 49002014, 2015, 2016, 2017, 2018, 2019, 2020, 2021
WESTERN STAR 49X2021
WESTERN STAR 57002014, 2015, 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
22V3380002022-05-16. EQUIPMENT:OTHER:LABELS
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
20V6340002020-10-14. EQUIPMENT:OTHER:LABELS; TIRES
20V2110002020-04-10. EQUIPMENT:OTHER:LABELS
19V1370002019-02-27. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; POWER TRAIN:AUTOMATIC TRANSMISSION:GEAR POSITION INDICATION (PRNDL)
20187142018-12-19. Powertrain

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