# Service bulletin M1691

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.

- Type: Service bulletin
- NHTSA id: 11020178
- Published by NHTSA: 2025\-07\-03
- Manufacturer's number: M1691
- Manufacturer's date: 2025\-06\-17
- NHTSA component: ELECTRICAL SYSTEM; SERVICE BRAKES

## NHTSA's summary

SERVICE BULLETIN M1691: LINKED BRAKING FUNCTIONAL IMPROVEMENT. PURPOSE: Initial Release. This bulletin inform dealers that there is an Electro Hydraulic Control Unit \(EHCU\) update available. This update is to improve functionality of the Linked Braking System. Linked Braking allows for more balanced front and rear braking under a wide variety of brake applications. At speeds greater than 20 mph \(32 km/h\), the system dynamically adjusts the linking to achieve better braking balance, as compared to single input braking. The EHCU update improves Linked Braking with optimized front and rear brake proportioning while only the rear brake is being applied by the rider. This software update is to address a possible customer concern related to the smoothness of brake engagement during a linked braking event when only rear brake is applied. If a customer has concerns on this Linked Braking operation under these conditions, this improvement update can be applied. NOTE: For vehicles within factory warranty and concern is present, submit a warranty claim per Table 4.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2025/MC-11020178-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2025/MC-11020178-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Brakes, Electrical system

## Vehicles listed

- 2024 to 2025 HARLEY\-DAVIDSON FLHX
- 2023 to 2024 HARLEY\-DAVIDSON FLHXSE
- 2025 HARLEY\-DAVIDSON FLHXU
- 2024 to 2025 HARLEY\-DAVIDSON FLTRX
- 2025 HARLEY\-DAVIDSON FLTRXRRSE
- 2023 to 2025 HARLEY\-DAVIDSON FLTRXSE
- 2024 to 2025 HARLEY\-DAVIDSON FLTRXSTSE

JSON: [/v1/bulletins/11020178](/v1/bulletins/11020178)

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