Technical service bulletins are instructions a manufacturer sent its dealers about a known fault. They are not recalls and the work is usually not free, but they are the clearest signal of a problem the manufacturer already knows about.
M1490
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1490 (V 26.8.3): DIGITAL TECHNICIAN II - UPDATES AND RELEASE NOTES. PURPOSE: Revision. This bulletin informs dealers that Harley-Davidson has made a software update to Digital Technician II (DT II). DIGITAL TECHNICIAN II (PART NUMBER: HD-48650). Version Version 26.8.3, Release Date: Week of July 24, 2026. NOTE: Software version (26.4.3) will need to be manually installed only if current software version of DT II is (26.0.2). After (26.4.3) is manually installed, automatic updates will bring DT II to the latest software version. Refer to bulletin M1713 for instructions. New Features - Harley-Davidson: 2023-2024 Touring: Updated Electronic Control Module (ECM) calibration offerings. LiveWire: S2DM/MH/AP: Calibration bundle 10.2.28: Telematic Control Unit (TCU) reflash updates. Change: Vehicle Setup: Body Control Module (BCM) – Tire Pressure Monitoring System (TPMS) Replacement: Correct issue where tire size selections were not available. System Info – Auxiliary Load Controller (ALC): Added Bike configuration field. Data Items – Trike ECM: Improved display of Gear Position when in reverse. Amp – Added support for (Part No. 76001619).
M1679
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1679: AFTERMARKET EXHAUST HEADER DEBRIS. PURPOSE: Initial release. This bulletin informs dealers that Harley-Davidson has identified instances of premature engine failure due to abrasive particle wear, specifically from debris inside new aftermarket exhaust headers. Recent evaluations have identified that certain newly manufactured exhaust headers may contain residual hard particles that, if not removed prior to installation, can migrate through the engine system and cause accelerated component wear or severe mechanical damage.
M1713
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1713 (REV C): DTII UPDATE PROCEDURE FOR SOFTWARE VERSION (26.4.3). PURPOSE: Revision C. This bulletin informs dealers that an issue was discovered in the Digital Technician II (DT II) software version (26.0.2), released on November 18, 2025. The issue prevents automatic software updates to be installed on your DT II computer. A manual installation of the latest DT II software version (26.4.3) will need to be performed if current DT II software version is (26.0.2), to allow future automatic updates. If a manual update to (26.1.5) or (26.3.2) has previously been completed, DT II will automatically update to (26.4.3) and no additional action is needed.. Revision C. Updated: Purpose for Service Bulletin and Required Dealer Action. Updated to Software Version (26.4.3).
M1391A
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1391A (REVU): MIDTRONICS GRX-3110 AND DCA-8000 SOFTWARE. PURPORSE: Revision U. The purpose of this bulletin is to inform the dealer network that a software update to the GRX-3110 and DCA-8000 is now available. DYNAMIC DIAGNOSTIC CHARGER SYSTEM (PART NUMBER: DCA-8000). [Rev U] Added: Description of improvements made to the testing algorithm for GRX software Version P and DCA-8000 software Version E.
PAB1171
Service Bulletin/Repair Instructions
GENUINE MOTOR PARTS AND ACCESSORIES BULLETIN PAB1171 (REV B): SOFTWARE UPDATE FOR SCREAMIN EAGLE PRO STREET TUNER. PURPOSE: Revision B. Updated: Summary. The App has returned to the Apple App Store. This bulletin informs dealers that a recent software update to the Screamin' Eagle Pro Street Tuner application will require the use of a Personal Computer (PC) to complete a Bluetooth Communication Interface (BCI) firmware update.
M1612
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1612: MILWAUKEE-EIGHT AND TWIN CAM TRANSMISSION GEAR PACKS. Purpose: This bulletin informs dealers that all: ⢠Twin Cam gear packs on CVO, Dyna, Police, Softail, Touring & Trike models and ⢠Milwaukee-Eight gear packs on CVO, Police, Softail, Touring & Trike models ordered after December 04, 2023 will not come with the shift drum, forks, shafts and related hardware.
TA0006
Service Bulletin/Repair Instructions
Harley-Davidson is aware of conditions that may result in a streaking appearance or film residue on the inside of some instrument gauges including speedometer and tachometers. This may occur after exposure of the vehicle to humid conditions. This condition may remain even after the moisture has evaporated.