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).
M1692
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1692: REVOLUTION MAX OIL SYSTEM SCAVENGE SCREEN. PURPOSE: Initial Release. This bulletin informs dealers that all 2026 Revolution® Max Powertains will come equipped with oil scavenge screens installed in the clutch and water pump cavities of the oil system. Oil scavenge screens prevent debris from entering the oil pump, potentially causing damage that would require additional inspection and repair to the bottom end of Revolution® Max Powertrain.
W146
Warranty Program/Extension
WARRANTY BULLETIN W146 (REV C): TIRE TREAD DEPTH GUIDE-UPDATE. PURPOSE: [Revision C. Updated: Tire Tread Depth Guide. Add tire part numbers 43100063, 43200035,43100029A, 43100033A and 43200045A.] To provide tire tread depth specifications for the dealership network to consult when filling warranty claims on used tires. Please see the Warranty Manual of your region for tire policy guidelines.
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.
M1555
Warranty Program/Extension
SERVICE BULLETIN M1555 (REV H): BATTERY WARRANTY GUIDELINES. PURPOSE: This bulletin informs the dealership network that Harley-Davidson has provided guidelines for battery warranty. REV H. Update section headers: AGM and Lithium-Iron Phosphate Batteries. Add graphics and callouts. Updated: Information on Battery.
PAB1165
Service Bulletin/Repair Instructions
GENUINE MOTOR PARTS AND MOTOR ACCESSORIES BULLETIN PAB1165 (REV A): H-D SYN3 SAE 15W50 / SAE 50 AVAILABILITY. PURPOSE: Revision (A) * Updated: Summary, Update table. This bulletin informs of the availability of the SYN3 New Improved Formula, a dual weight SAE 15W50 / SAE 50 Motorcycle Oil. The new formula transitions into inventory as the old SYN3 20W50 product inventory is depleted. Availability varies by SKU and region. The original SYN3 20W50 will be obsoleted when the transition is complete.
M1663
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1663: REVOLUTION MAX INSTRUMENT MODULE SOFTWARE UPDATE. PURPOSE: This bulletin informs the dealers that there is a new Instrument Module (IM) software (LM7_51456370_20240322) and (LM4_51456370_20240325). Refer to: Infotainment Support Resources page on Service Information Portal (SIP).
M1655
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1655: REVOLUTION MAX CLUTCH CABLE FREE PLAY SPECIFICATION. PURPOSE: This bulletin informs dealers that the clutch cable free play specification has been updated on all Revolution® Max vehicles. Original specification: Dimension: 0.039–0.079 in (1–2 mm). Free play has now been changed to: Dimension: 0.079–0.118 in (2–3 mm). All online electronic service manuals and future publications will reflect this information.
M1654
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1654: DTII MODULE REPLACE MENU CHANGE. PURPOSE: This bulletin informs dealer technicians that there is a new menu item in Digital Technician II (DT II). DT II now has a stand alone Module Replace menu inside of Vehicle Setup. This will allow you to program the factory settings, for the connected vehicle, to the Electronic Control Module (ECM), Body Control Module (BCM) and Infotainment Control Unit (IFCU) (if equipped) in a single menu. Initial Release. 8/7/2024.
M1634
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1634 (REV A): SWITCHBACK SEAT FOR NIGHTSTER. PURPOSE: To inform dealers of a seat support cable issue with the initial shipment of Switchback Seats (Part No. 52000655) that will require a replacement with Seat Support Cable (Part No. 52100087). In the initial shipment of Nightster Switchback Seats, the seat support cable used to limit the seat opening while accessing the fuel tank was installed to the seat in the incorrect location. Compared to the stock seat, this creates a reduction in available space to access the fuel tank.
M1631
Service Bulletin/Repair Instructions
SERVICE BULLETIN M1631: REVOLUTION MAX OIL CHECK PROCEDURE UPDATE. PURPOSE: To inform dealers of a new procedure for checking oil levels on Revolution® Max powered vehicles. The procedure has been updated to account for potential concerns of a low oil fill condition when set on the side stand. This condition could be caused by having varying degree lean angles of the vehicles in the Revolution® Max family while utilizing the same dipstick. Compounding this is the difference in lean angle of vehicles that come equipped with Adaptive Ride Height (ARH) set in the locked position (high) and set to drop when coming to a stop (low). To remedy this potential concern, the final step in checking the oil level will now be performed with the oil at operating temperature in the upright position for consistency across vehicle family and suspension settings. The side stand markings on the dipstick will only be used for a quick reference. NOTE: Oil levels checked on the side stand may read high after servicing the oil level in the upright position hot. This is a normal condition.