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 26.0.2): 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). New Software Update Version 26.0.2. Release Date: Week of November 18, 2025. New Features, Changes. 2026 Vehicles, 2025 Softail and LiveWire S2DM/MH/AP EV3. NOTE: Digital Technician II (DT II) supports additional Harley-Davidson motorcycle models and model years outside of those listed.
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.
M1684
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1684: MARKET SPECIFIC BATTERY INTRODUCTION. PURPOSE: Initial Release. This bulletin informs dealers of the availability of new batteries for new Original Equipment (OE) vehicle production and in the Parts and Accessories (P&A) catalog. Availability of the new Absorbed Glass Mat (AGM) batteries will vary by market and will be transitioning over the next few months. NOTE: The ring terminal screws are not compatible between Leoch and East Penn batteries. The new batteries will include new ring terminal screws, which must be used. The ring terminal screws from the old battery need to be discarded.
M1650
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1650: MILWAUKEE EIGHT AND TWIN CAM CAMSHAFT DRIVE GEAR RETENTION KIT CHANGES. PURPOSE: This bulletin informs dealers that changes have been made to the Camshaft Drive Gear Retention Kit and service proceduresfor the Milwaukee-Eight and Twin Cam applications. In an effort to increase the clamp load of the camshaft drive sprocket bolted joint and prevent the drive bolt from loosening in high lift camshaft applications, the following changes have been made: a. The camshaft drive bolt final torque has been increased to 40 ft-lbs (54 N·m) for all Milwaukee-Eight and certain Twin Cams models. See Vehicles Affected. This increase in torque will make the bolt a one time use application. Never re-use a camshaft drive bolt for service after tightening to the increased specification. See service manual for updated procedure. b. A new camshaft drive gear retention kit (Part No. 91800088) has been created. This new kit is compatible with all Milwaukee-Eight and Twin Cam engines using Parts and Accessories (P&A) camshaft and Original Equipment (OE) camshaft applications. See Instruction sheet for specific fitment on Twin Cam OE camshaft applications. The new kit utilizes friction washers to prevent unwanted rotation of components in the drive sprocket bolted joint under stress. The use of liquid threadlocker on the threads of the bolt and pre-lube to the head of the bolt flange and outside of the washer help the bolt reach full stretch when tightening. NOTE: Engines produced at all Harley-Davidson Motor Company (HDMC) plants will not come with the new kits installed. They will continue to be produced with (Part No. 25566-06).
M1555
Warranty Program/Extension
SERVICE BULLETIN M1555 (REV E): BATTERY WARRANTY GUIDELINES. PURPOSE: Revision E. Added: Added procedures for the DCA-8000 E Battery Tester.* Updated: All sections. This bulletin informs the dealership network that Harley-Davidson has provided guidelines for battery warranty.
PAB1158
Service Bulletin/Repair Instructions
GENUINE MOTOR PARTS AND MOTOR ACCESSORIES BULLETIN PAB1158: OIL FILTER PACKAGING AND CASE QUANTITY UPDATE. PURPOSE: To inform dealerships that Harley-Davidson has made updates to oil filters including new part numbers, packaging design, and bulk case quantity changes.