691 Brake Lock Systems

Locks hydraulic pressure in the service brakes to supplement the vehicle's mechanical parking brake and provide extra holding in heavy-duty and high-frequency applications. The 691 Brake Lock significantly enhances vehicle holding capability while not interfering with normal service brake function.

The MICO® 691 Brake Lock can be interlocked with other vehicle components/systems such as a power takeoff control, bus door or wheelchair lift to insure the brakes are locked whenever those components/systems are being utilized.


  • Automatically monitors and maintains optimal brake lock system pressure
  • Provides ability to lock up to four channels with different actuators
  • Can be controlled remotely
  • Activates with flip of a switch
  • Can be diagnosed using LEDs
  • Comes with waterproof control module and weather proof connectors


Related Product Information

691 Electrohydraulic Brake Lock System (Form Number 80-690-001)

This 4-color brochure introduces the 691 Brake Lock System and focuses on the individual 691 components. Features, benefits, dimensional drawings, and basic operation instructions are also included.

Brake Lock Application Guide (Form Number 80-950-152)

A 16-page application guide that covers the different types of MICO Locks and vehicle brake systems. Includes a list of both domestic and imported trucks with specific vehicle and lock information.

MICO 691 Lock System Manual (Form Number 81-690-032)

This 24-page service manual includes installation, operating, and trouble shooting information. Coded wiring diagrams and a specific 691 Models/Replacement Parts Table are also included.

MICO Product Guide (Form Number 80-950-006)

This is our introductory catalog  for MICO Products. Introductory catalog for MICO Products providing product photos and brief descriptions that cover MICO's product portfolio offerings in brakes, brake actuation, valves, and controls.