Micon 691 User Manual

Operation and Installation Instructions

691 LOCK SYSTEM

READ GENERAL INSTALLATION GUIDELINES SHEET (FORM NO. 81-600-001) BEFORE PROCEEDING.

1. The MICO 691 System is a supplemental safety
device which provides additional brake holding
action when used with existing vehicle parking
brake. It is not for dynamic service braking.

2. The 691 System must be used in combination with
an audible and/or visual alarm as a warning to
signal the user of any loss of brake system pres­sure. Do not disconnect warning devices.

3. All lines, fittings and surrounding areas must be
cleaned of dirt or road residue before any lines or
fittings are disconnected. Special care must be
taken so dirt and road residue are not allowed to
enter the hydraulic brake system. This can con­taminate the system and interfere with proper
operation of brakes and MICO 691 System.

4. Follow procedures outlined in Vehicle Manufac­turer’s Service Manual or SAE Standards when
making new connections or adding to existing
brake systems. Use only steel brake tubing con­forming to SAE specifications.

5. Vehicle Brake System: Always use clean fluid
conforming to vehicle manufacturer’s recommen­dations. 691 Power Unit: See BEFORE
PROCEEDING, page 3 for proper fluid type.
Improper or contaminated fluid may cause gummy
deposits, softening and swelling of rubber seals,
and may render the 691 System inoperative.
Such a condition must be corrected immediately.

6. Do not use sealants, tapes, teflon or cement
compounds on any connections or fittings. These
sealants or compounds can contaminate the
hydraulic brake system and interfere with the
operation of brake components or MICO 691
System.

7. All fittings and connections must be in good
condition and properly torqued.

8. Brake hoses, brake lines, MICO 691 System,
brake components, cylinders, and all fittings must
be routinely inspected for leaks, damage or wear.
Proper fluid levels must be maintained. In the
event of any loss of fluid, brake system must be
carefully inspected for leaks.

9. When installation of MICO 691 System is com­plete, 691 System and brake system must be
bled of air. Bleed MICO 691 System according to
procedures outlined in this manual. Bleed brake
system according to vehicle manufacturer’s
recommendations.

10. The self-adhesive warning labels, page 1, ac­companying each MICO locking device must be
affixed in the vehicle cab in view of operator.

11. Keep this manual in the cab of the vehicle after
installing the 691 System.

MICO could not possibly know of and give advice with respect to all conceivable applications in which this product may be used and the possible hazards and/or
results of each application. MICO has not undertaken any such wide evaluation. Therefore, anyone who uses an application which is not recommended by the
manufacturer, first must completely satisfy himself that a danger will not be created by the application selected, or by the particular model of our product that is
selected for the application.

MICO has made every attempt to present accurate information in catalogs, brochures and other printed material. MICO can accept no responsibility for errors
from unintentional oversights that may exist. Due to a continuous program of product improvement, materials, specifications, and product documentation are sub
ject to change without notice or obligation.

MICO is a registered trademark of MICO, Incorporated. MICO is registered in the U.S. Patent and Trademark Office as well as in Australia, Canada, Great Britain, Indonesia, Japan, Peoples Republic of China, and South Korea.

MICO, Incorporated MICO West Division

1911 Lee Boulevard (Zip Code 56003-2507) 701 East Francis Street (Zip Code 91761-5514)

P.O. Box 8118 / North Mankato, MN U.S.A. 56002-8118 P.O. Box 9058 / Ontario, CA U.S.A. 91762-9058

( 507.625.6426 Facsimile 507.625.3212 ( 909.947.4077 Facsimile 909.947.6054

Form No. 81-690-032 Revised Online 11/30/06 Printed in U.S.A.

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Table of Contents

Page

SELF ADHESIVE LABELS ................................. 1

INTRODUCTION ...................................... 2

PRINCIPLE OF OPERATION ................................ 2

INSTALLING A 691 SYSTEM................................ 3

IDENTIFY YOUR BRAKE SYSTEM ............................ 3-4

DIMENSIONAL DATA ................................... 5

MOUNTING ......................................... 6

Actuator .......................................... 6

Power Unit ........................................ 6

Control Module ...................................... 6

User Interface ....................................... 6

PLUMBING ......................................... 7

Single 691 Brake Lock System .............................. 7

Dual 691 Brake Lock System ............................... 7

3 Channel Anti-Lock 691 Brake Lock System ....................... 8

4 Channel Anti-Lock 691 Brake Lock System ....................... 8

WIRING ........................................... 9

Wiring Instructions..................................... 9

Connecting External Inputs ................................ 9

Connecting the Vehicle Horn ............................... 9

Connecting Power for the Control Module ........................ 9

BLEEDING ......................................... 10

Tips on Bleeding Brake Systems ............................. 10

Bleeding Procedures .................................. 10-11

HORN WARNING CIRCUIT TEST ............................. 11

691 OPERATING INSTRUCTIONS ............................ 11

Using 691 as a Lock System ............................... 11

Using 691 as an Interlock................................. 12

691 System Installation Checklist ........................... (Insert)

BRAKE LOCK APPLICATIONS (Wiring Diagram) ....................14

INTERLOCK APPLICATIONS (Wiring Diagram) ..................... 15

TROUBLESHOOTING .................................. 16-18

691 MODEL NUMBERS ................................. 19-20

691 ACCESSORIES .................................... 19

SELF ADHESIVE LABELS

NOTE

All 691 models include the self adhesive labels shown below. Determine which labels are used in your application.

THISNOTICEMUST BE AFFIXEDONDASHINVIEWOFOPERATOR

!

WARNING

Serious injury
or death can
occur if these
instructions are
not followed

This vehicle is equipped with 691 Brake Lock System.

Operator must read and understand warnings and
operating instructions before using vehicle (Form no.
81-690-032) .

Do not use 691 Brake Lock in place of original equip­ment parking brake.

Always apply parking brake and other provided hold­ing devices when using 691 System.

Do not use 691 Brake Lock for overnight or prolonged
parking.

Release 691 Brake Lock before moving vehicle.

691 Brake Lock and warning circuit are disabled if
battery power is lost or disconnected.

PREVENT
ROLLAWAY

Use in all applications.

THISNOTICEMUST BE AFFIXEDONDASHINVIEWOFOPERATOR

Operator must read and

understand Warnings and

Operating Instructions before

using vehicle

(Form no. 81-690-032).

691 Brake Lock

TO LOCK:

1. Set parking brake

2. Move lock switch to LOCK position

TO RELEASE:

1. Move lock switch to RELEASE position

2. Release parking brake

Use in all applications
using a user interface.

THISNOTICEMUST BE AFFIXEDONDASHINVIEWOFOPERATOR

!

WARNING

Serious injury or death can occur if
these instructions are not followed.

Operator must read and understand warnings
and operating instructions before using vehicle
(Form no. 81-690-032).

This vehicle is equipped with a 691 Brake Lock
System that is activated by a remote input.

Unintended operation of the remote input will
cause the brakes to apply or release without
warning.

The operator must understand the function of
the remote inputs.

Be aware of all conditions that will cause the
691 Brake Lock System to activate or deacti­vate without user intervention.

Use in all applications where the

691 System is remotely activated.

1

INTRODUCTION

Vehicles today have two separate brake systems. One is
the service brake system and the other is the parking
brake system. The service brake system is used to slow or
stop a vehicle during normal operation. The parking brake
system is usually cable operated and used to hold the
vehicle stationary while parked.

Experience has shown that some vehicle applications re
quire more brake holding capacity than provided by prop
erly maintained parking brakes. The MICO 691 Brake
Lock System uses the vehicle service brakes to supple
ment the parking brake. The 691 System provides pres
sure to the service brake system in the same manner as
when the vehicle operator presses on the brake pedal.

The 691 also provides external inputs which can activate
the system without direct operator interjection.

The 691 Brake Lock System consists of:

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The Control Module and User Interface

(Figure 1)

The control module controls operation of the system
through the user interface or remote activation. The
user interface incorporates a manually activated switch,
audible alarm, and "locked" lamp.

Control Module

User Interface

FIGURE 1

The Power Unit (Figure 2)

The power unit uses a 12 volt DC pump to produce
pressure in the vehicle service brake system to lock
the brakes. The pump reverses flow to release locking
pressure.

Two pressure switches are located on the power unit.
The pressure switches sense the pressure that the
power unit is producing. The high pressure switch
starts and stops the pump while pressurizing the sys­tem. The low pressure switch starts and stops the
pump while releasing pressure from the system.

Although the power unit contains a built in fluid
reservoir, a remote reservoir is available as an option
for special applications. Refer to 691 Accessories chart
on page 19.

The Actuator (Figure 3)

The actuator is a mechanical device that links the
hydraulics of the 691 System to the vehicle service
brake system. The actuator separates the 691 System
fluid from the vehicle service brake system. Various
actuators are available for use in different types of
service brake systems.

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PRINCIPLE OF OPERATION

1. When the 691 System is activated, the control module
starts the power unit pumping fluid into the actuator(s).
As the actuator(s) become pressurized they isolate the
vehicle master cylinder and pressurize the service
brakes.

When lock pressure is reached, the high-pressure
switch signals the control module to stop the pump.

While the pump is stopped, locking pressure is held in
the brake system. If locking pressure drops, the high
pressure switch signals for the power unit to turn "on"
and restore locking pressure.

2. When the 691 System is deactivated, the pump
reverses and releases pressure. The actuator releases
pressure from the brakes and opens the ports to the
vehicle master cylinder. When locked pressure returns
to zero psi a signal from the low-pressure switch stops
the pump.

Brake System fluid and 691 Sys
tem fluid always remain isolated
from one another.

FIGURE 3

NOTE

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FIGURE 2

2

INSTALLING A 691 SYSTEM

There are four steps to installing the 691 System.

1. Mounting

2. Plumbing

3. Wiring

4. Bleeding

The 691 System must only be installed by someone with
good working knowledge of automotive brake and electri

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cal systems.
It is important that the installer of the 691 System under

­stands fluid types used in various 691 Systems. Read and
understand this instruction manual before installing the 691
Brake Lock System.

Brake System Fluid

For all 691 installations the vehicle’s brake system
fluid does not change. Vehicles currently using

brake fluid in the brake system will continue to use
brake fluid. Vehicles currently using mineral base
hydraulic oil in the brake system will continue to use
mineral base hydraulic oil.

BEFORE PROCEEDING:

1. Identify your vehicle brake system. See pages
3&4.

2. Be sure you have the correct 691 model number
and it contains all the parts. Refer to Table 1 (pages
19 & 20).

All vehicles currently using automotive brake
fluid (DOT 3, 4, 5 or 5.1) in the brake system must
use the 691 model numbers designated (SF). All
vehicles currently using mineral base hydraulic oil in
the brake system must use the 691 model numbers
designated (HO).

3. Check brake pedal height and feel. With the vehicle
running, push on the brake pedal until there is no
more forward movement. Measure and record the
distance from pedal to floor. Brake pedal height and
"feel" will be the same after the 691 System is in­stalled, refer to Figure 4.

691 System Fluid

The two 691 Power Unit designs, DOT 5 silicone fluid
(SF) and mineral base hydraulic oil (HO), assure seal
compatibility with your existing brake system.

NOTE: Power unit and brake system fluids do not
become intermixed when a 691 System is installed.
The 691 Actuator(s) isolate the 691 System fluid
from the brake system.

IDENTIFY YOUR BRAKE SYSTEM

Typical hydraulic braking systems in use today vary
depending on manufacturer and size of vehicle. For in
stance, a vehicle equipped with a single system may have
a firewall mounted booster or possibly a frame mounted
remote booster. The same holds true for the dual and split
systems. The rear wheel anti-lock system is a dual brake
system with an anti-lock valve installed. All-wheel anti-lock
systems are defined as 3-channel or 4-channel systems

FIGURE 5

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Typical Single System

One single hydraulic system serving both front and rear brakes.

Identifying Feature:

1.One line from master cylinder.

691 Actuator Position:

(1) Front axle (2) Rear axle (3) 4-wheel

FIGURE 4

(Check the number of outlet lines from the anti-lock control
valve). To be absolutely sure which braking system your
vehicle is equipped with, check it. Look for identifying fea
tures such as dual flex lines at rear axle or front wheels,
number of master cylinder lines, anti-lock valve(s), etc.
Then, compare with the circuits shown in Figures 5 thru

11.

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FIGURE 6

Typical Dual System (Vertical Split)

Two independent braking systems. One system leads to the front brakes and the
other system to the rear brakes.

Identifying Feature:

1.Two lines from master cylinder.

2.Combination valve (used on some models).

691 Actuator Position:

(1) Front axle (2) Rear axle* (3) 4-wheel

* Some imported vehicles use two separate air boosted master cylinders.

3

FIGURE 7

Typical Split System (1 1/2 x 1/2)

Two independent braking systems. One system leads to the front and the rear
brakes and the other system leads only to the rear brakes.

Identifying Feature:

1.Two lines from master cylinder.

2.Single hose to each front wheel.

3.Two hoses to rear axle.

691 Actuator Position:

(1) Front axle (2) Rear axle (3) 4-wheel

CAUTION: Whether position 2 or 3 is used, both halves of system must be

locked.

FIGURE 8

FIGURE 9

FIGURE 10

Typical Rear Wheel Anti-Lock System

Two independent braking systems. One system leads to the front brakes and the
other system to the rear brakes.

Identifying Feature:

1.Two lines from master cylinder.

2.Anti-lock control valve between master cylinder and rear wheels.

691 Actuator Position:

(1) Front axle (2) Rear axle (3) 4-wheel

(Dual Vertical Split)

Imported Truck 3-Channel All-Wheel Anti-Lock System

Provides braking control by way of independent anti-lock channels for each rear
wheel and a third channel for the front wheels.

Identifying Feature:

1.Three separate air/hydraulic brake boosters.

2.One line to front brakes.

3.Separate lines to each rear wheel.

691 Actuator Position:

(1) Front axle (2) Rear axle (1 & 2) 4-wheel

NOTE: The anti-lock functions on air booster system, not the hydraulic side.

Typical 3-Channel All-Wheel Anti-Lock System

Provides braking control by way of independent anti-lock channels for each front
wheel and a third channel for both rear wheels.

Identifying Feature:

1.Two lines from master cylinder to anti-lock valve(s).

2.One line from anti-lock valve to rear brakes.

3.Separate lines from anti-lock valve to each front wheel.

691 Actuator Position:

(1) Front axle (2) Rear axle (1 & 2) 4-wheel

NOTE: Some 3-channel anti-lock brake systems use two separate anti-lock

valves.

FIGURE 11

Typical 4-Channel All-Wheel Anti-Lock System

Provides braking control by way of an independent channel for each front wheel
and each rear wheel.

Identifying Feature:

1.Two lines from master cylinder to anti-lock valve.

2.Separate lines from anti-lock valve to each of the front and rear wheels.

691 Actuator Position:

(1) Front axle (2) Rear axle (1 & 2) 4-wheel

NOTE: Some 4-channel anti-lock brake systems use two separate anti-lock

valves.

4

DIMENSIONAL DATA

1 1/4" Diameter Bore Dual Actuator 1 1/4" Diameter Bore Single Actuator

1 3/4" Diameter Bore Dual Actuator 1 3/4" Diameter Bore Single Actuator

Power Unit

Control Module

millimeters

inches

User Interface

Remote Reservoir - (optional)

See 691 Accessories on page 19

5

MOUNTING

Several self adhesive labels are supplied with each 691
Brake Lock. Determine which labels are used in your
application and affix in the vehicle cab in view of the
operator. See page 1.

Actuator

1. Repeat the mounting procedures for each actuator
used in your system.

2. Find a location, preferably on the frame rail away from
heat, where the actuator(s) will mount allowing easy
access to brake lines, refer to Figure 12. The actua­tor(s) must be mounted horizontally below the level of
the vehicle master cylinder. The bleeder screws must
be in an upright position. Relocate the bleeder screws
as necessary to maintain upright position. Torque
bleeder screws 17.6-20.3 N-m (13-15 lb-ft).

FIGURE 12

power unit reservoir. Check the CAUTION label
around the power unit reservoir breather/filler plug
to verify fluid type, refer to Figure 13.

Control Module

1. A mounting bracket is provided with the 691 Control
Module to mount the control module directly to the
691 Power Unit. See power unit dimensional drawing
on page 5. The control module can be mounted on top
of the power unit as shown, as well as mounted to
either side. The control module can also be mounted
to position the harness connection in the opposite
direction shown.

2. When the 691 Control Module is not mounted to the
691 Power Unit, an optional 11' wire harness
(32-820-022) is available from MICO, Inc. See page
19 for 691 Accessories.

RECOMMENDED ACTUATOR
MOUNTING LOCATION ­INSIDE OR OUTSIDE FRAME RAIL

3. Using the actuator mounting brackets as a template,
mark and drill four 11/32" diameter holes. Fabricated
mounting brackets can be used to mount the actua­tor(s). The strength of fabricated brackets must be
adequate to prevent flexing of brake lines.

4. Install the actuator using four 5/16-18UNC, grade 5,
bolts, lock washers, and nuts. Torque 27.1-33.9 N-m
(20-25 lb-ft).

5. Install the brass adapters from the fitting package
in the actuator ports and torque 7.9-10.2 N-m
(70-90 lb-in).

Power Unit

1. The power unit can be mounted horizontally in the
engine compartment, on the frame rail, or in the cab.
However, it must be protected from dirt, moisture and
possible impact. Easy access to the reservoir
breather/filler plug must be maintained to allow for
filling and checking fluid level. The reservoir breather
plug must be kept in an upright position. If this is not
possible a remote reservoir can be installed, refer to
691 accessories on page 19.

2. Mark and drill two 7/16" diameter holes 2 5/16" apart.
Fabricated mounting brackets can be used.

3. Mount the power unit using two 3/8-16UNC bolts and
lock washers.

4. 691 models designated (HO) must use mineral base
hydraulic oil in the power unit reservoir. 691 models
designated (SF) must use DOT 5 silicone fluid in the

FIGURE 14

User Interface

1. A dash mounted user interface is provided for use by
the operator in the cab. The user interface includes a
manually activated switch, audible alarm, and "locked"
lamp. Find a mounting location in the cab of the
vehicle where:
A. The operator has easy access to the "lock" -

"release" rocker switch.
B. The "lock" lamp is visible to the operator.
C. It is protected from having something spilled on it.
D. There is easy routing of wires from the 691

Control Module to the user interface.

2. The user interface is not necessary for applications
where the 691 System is activated by other manual
switches or electrical interlocks.

NOTE

When the 691 User Interface is not installed with this
system, another visual identifier must be used to inform
the operator that the 691 System is "locked". See sche
matic on page 14.

FIGURE 15

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FIGURE 13

Pressure
Switches

CAUTION Label

6