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Service bulletin M-834-001 202401

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 id10249557
Published by NHTSA2024-02-02
Manufacturer's numberM-834-001 202401
Manufacturer's date2024-01-01
NHTSA componentELECTRICAL SYSTEM

NHTSA's summary

TSB: Some Mack MMD trucks could experience an issue with the ignition lock cylinder sticking. Trucks that experience a sticking lock cylinder could have a lock cylinder that becomes tight or sticks in the start position. If the above condition is found replace the ignition lock cylinder.

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

Electrical system

Vehicles listed
MACK MD2020, 2021, 2022, 2023, 2024

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
CBR 2712-7 0320262026-04-02. Service bulletin. CBR - No Start Condition After Over the Air Programing.
CBR 2128-7 2026012026-02-03. Service bulletin. CBR - Engine Control Module (EMS) Software Information - Improvement List (Change Log), US21+OBD2021 Emissions ONLY
CBR 2172-5 0820252025-09-02. Service bulletin. CBR - When an OTA (Over-The-Air) job starts to program the VECU blocks the starter relay out, if the job ends in a Critical failure, the vehicle will remain in Safe State.
CBR 407 0720252025-08-04. Service bulletin. CBR - To correct the MID136 SID 66 FMI 7 fault code the latest Bendix VCP file will need to downloaded.
CBR 2488 0720252025-08-04. Service bulletin. CBR - A significant GPS reporting issue is affecting fleet operations, with trucks maintaining back-office communication but failing to transmit GPS location data.
CBR-2350 2024072024-08-01. Service bulletin. CBR: Telematics Gateway (TGW) Connect Ability Issues
CBR-2333 2024012024-02-02. Service bulletin. CBR: TGW Will Not Connect After SIM Card Replacement
S3433 2023082023-09-06. Service bulletin. Service Campaign: MMD Steering Column Harness Routing
CBR-2112 2023072023-08-02. Service bulletin. CBR: Programming Failure - Chassis With Cummins Engine And An Allison Transmission
S34332023-07-06. Service bulletin. Campaign - Mack trucks has determined that certain model year 2022 Mack Medium Duty (“MMD”) vehicles, require an inspection of the steering harness routing.