Ford Falcon. Manual — part 71

206-06-4 Hydraulic

Brake

Actuation 206-06-4

DESCRIPTION AND OPERATION (Continued)

rear brake system inlet and outlet ports of the master

Operation

cylinder.

The Booster Servo Unit is designed to assist the effort

When the brake pedal is applied, the full rear brake

applied by the driver’s foot on the brake pedal. It uses

fluid pressure passes through the proportioning valve

the vacuum created in the engine inlet manifold to

to the rear brake hydraulic system until the valve split

boost force applied at the master cylinder push rod in

point is attained. Above the split point, the

an exact and controlled manner.

proportioning valve reduces hydraulic pressure to the

The assembly is mounted between the brake pedal

rear brakes for balanced braking.

and the master cylinder, with the push rod from the

The proportioning valve for ¾ tonne non ABS utes

rear of the unit connected to the brake pedal, and a

has a 2.5 MPa split point, on the end face of the

push rod from the front of the unit abuts the master

master cylinder body.

cylinder piston.

NOTE: For 1 tonne non ABS utes, the master cylinder The force which assists the pedal effort is obtained by

does not contain proportioning valve, split point is

admitting atmospheric pressure to one side of the

shown as ‘C000’ stamped on outside of cylinder.

diaphragm which is suspended in a vacuum. The

Proportioning in this case is handled via a load

difference in pressure moves the diaphragm/s and

sensing proportioning valve located over rear axle.

this movement is used in a controlled manner to

augment the driver’s pedal effort.

Pressure Differential Valve (where fitted on non

In the case of a vacuum failure, the valve and rod

ABS vehicles)

assembly of the servo and the master cylinder push

The brake fail warning light switch is mounted in the

rod act as a single push rod. The brakes will,

valve body with the spring-loaded plunger fitting into a therefore, work in the conventional manner, but more

tapered groove in the centre of the spool. With the

effort will be required on the brake pedal.

spool in a centralized position the switch contacts

Adjustable Pedal Box

remain open.

Description

Should there be a loss of pressure in either the front

or rear brake system, when the brake pedal is

The pedal box assembly is a unit construction

applied, the spool will move off centre closing the

comprising a reinforced plastic structure upon which

switch contacts and turning on the warning light on

the pedals, switchgear and adjustment motors are

the instrument panel.

mounted.

After repairs have been made and the brake system

The complete pedal box assembly can be removed

bled, when the brakes are applied the pressure in the from the vehicle as a single unit.

front and rear systems will equalize, centralizing the

The pedal assembly incorporates the ETC or drive by

spool and opening the switch contacts thus turning off

wire accelerator sender unit. In the adjustable version

the warning light.

the brake and accelerator pedals are height

adjustable via a aswitch on the side of the steering

Fluid Level Warning Switch (All ABS cars only)

column.

All ABS models have a fluid level warning switch and

Where applicable pedal adjustment is achieved by a

no differential switch.

single drive motor attached directly to the accelerator

The warning switch is dipped into the fluid reservoir

pedal with a drive cable running to a gear box on the

and interacts with a float within the fluid. When the

brake pedal, adjustment of brake and accelerator

fluid level drops below a predetermined level the

pedals is simultaneous.

switch activates, resulting in a warning light on the

instrument panel.

Acronyms and Abbreviations

Power Brake Booster

APM

Accelerator Pedal Module

PCM

Power Train Module

Description

BEM

Body Electronic Module

Both 6 and 8 cylinder vehicles are equipped with a

Step Over

Height Difference Between Brake and

twin diaphragm brake booster.

Accelerator Pedal

The brake booster is a self-contained

MSC

Memory Seat Controller

vacuum-hydraulic braking unit mounted on the engine

side of the dash panel.

PPS

Pedal Position Sensor

The brake booster is of the vacuum suspended type

which utilizes engine intake manifold vacuum and

atmospheric pressure for its power.
The booster unit is to be replaced, not repaired, if

found to be defective.

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206-06-5 Hydraulic

Brake

Actuation 206-06-5

DESCRIPTION AND OPERATION (Continued)

Item

Description

1

Brake Pedal Transmission

2

Adjusting Cable

3

Potentiometer (Memory Only)

4

Adjusting Motor

5

APM

6

Adjusting Motor Transmission

7

Accelerator Pedal

8

Transmission Drive Cable

9

Brake Pedal

10

Brake Lamp Switch

11

Cruise Control Cut Off Switch (Brake)

12

Brake Booster Rod Pivot

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206-06-6 Hydraulic

Brake

Actuation 206-06-6

DIAGNOSIS AND TESTING

should have a thorough knowledge of brake system

Hydraulic Brake Actuation

operation and accepted general performance

guidelines in order to make good comparisons and

Inspection and Verification

detest performance problems.

Preliminary checks

Select a road that is reasonably smooth and level.

Gravel and bumpy roads, except to demonstrate ABS

NOTE: Always check the fluid level in brake master

function are not suitable. The surface does not allow

cylinder before carrying out the test procedures. If the

the tires to grip the road equally. Avoid crowned

fluid level is not at the correct level, fill the reservoir

roads.

with specified brake fluid.

A key factor in evaluating brake concerns is the

NOTE: Prior to carrying out any diagnosis, make

deceleration rate. This varies from vehicle to vehicle

certain that the brake warning indicator is functional.

and with changes in operating conditions. It is evident

Visually examine front and rear tires and wheel

how well the brakes are working after just a few

assemblies for damage such as uneven wear

applications.

patterns, tread worm out or sidewall damage.

Check these items before entering Diagnostics.

Make sure the tires are of the same size, type and,

Topic

Specification

where possible, same manufacture. Install a new tire

Brake Fluid

Ensure that the Reservoir is Filled

or wheel if it is damaged or excessively worm. Wheels

Reservoir

to the Max Point. Use Ford

and tires must be cleared of any foreign material and

Approved Brake Fluid Mobil ESZ -

tire pressures adjusted to the correct specification.

M6C55A.

If tires exhibit uneven wear or feathering, the cause

must be corrected. Check steering and suspension

CAUTION: Do not allow

components for damage or wear and, if necessary

brake fluid to contact vehicle

check and adjust front alignment.

paint work.

A change in brake pedal feel is usually the first

Vehicle Test

Ensure That Your Local State

indicator of a brake concern. The change may only be Drive to

Speed Limits are Not Exceeded

normal ABS function, but maybe sufficient cause for

Confirm Fault

further investigation. The brake warning indicator in

Battery Voltage Must be Greater Than 12 Volts

the instrument cluster and the brake fluid level in the

Obstructions

Check for Any Obstructions at the

brake master cylinder reservoir are also indicators of

Brake Pedal Area, Such as Floor

the system concerns.

Mats and Wiring Harnesses

If the wheel is locked and the vehicle must be moved,

open the bleeder screw at the locked wheel to let out

Visual Inspection Chart

enough fluid to relieve the pressure. Close the bleeder

screw. This bleeding operation may release the

Mechanical

Electrical

brakes but it will not correct the locked wheel

Brake Pedal

Fuse(s)

condition, repair the locked components before

Pedal Pad

Relay(s)

proceeding.

Adjustment

Wiring harness

mechanism

Electrical connector(s)

Brake Booster

Brake pedal switches

Inspect all hoses and connections, all unused vacuum

MSC

connectors should be capped. Hoses and their

connections should be correctly secured and in good

condition with no holes, soft or collapsed areas.

Road test

Perform a road test to compare actual vehicle braking

performance with the standard performances

expected by the driver. The ability of the test driver to

make valid comparisons and detect performance

deficiencies will depend on experience. The driver

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206-06-7 Hydraulic

Brake

Actuation 206-06-7

DIAGNOSIS AND TESTING (Continued)

Function Test

Condition

Possible Source

Function Test

Pin Point Test

Pedal Feel

Pedal Slow or does not

Manual Application Test of

206-06-B

return

the Brake Pedal to confirm

206-06-B

Binding / Raspy pedal

Manual Test

Worn Pedal Pad

Visual Inspection

Brake Lamp Switch

Not Functioning

Visual Inspection

206-06-C

Adjustment

Visual Inspection

Lack of Braking

Excessive Force

Manual Application Test of

Efficiency

Required

the Brake Pedal to confirm

Master Cylinder

Visual Inspection

Leakage

Manual Application Test of

Brake Booster

the Brake Pedal to confirm

Tyre Wear

Visual Inspection

Tyre Pressure

Pressure Check

Adjustable Pedal

Memory

Manual Application Test of

206-06-E

Adjustment Motor Fault

the Brake Pedal to confirm

310-02-C5 & 6

No Pedal Response

Measurement

Adjustment Cable

Brake and Accelerator

Pedal Heights Incorrect

Symptom Chart

Condition

Source

Action

Pedal Feel

Brake Pedal Not Returning on Release

Go to Pin Point Test 206-06-B

Braking System Diagnosis. Refer to

Excessive Pedal Travel

this section.

"Raspy" feel

Go to Pin Point Test 206-06-B

Pedal Binding at Pivot

Go to Pin Point Test 206-06-A

Replace Brake Pedal Pad. Refer to

Pedal Pad Worn

procedure in this section.

Obstruction at Pedal

Go to Pin Point Test 206-06-B

Braking System Diagnosis. Refer to

Poor Braking Efficiency

Faulty Brake Booster

this section.

Brake Disc Pads Worn

Refer to Brake section 206-03, 206-04.

Booster Rod Disconnected

Go to Pin Point Test E.

Vacuum Poor, Leaking or

Refer to Braking System Diagnosis.

disconnection at the Brake Booster

Refer to this section.

Cruise Control not turning off when

Refer to Braking System Diagnosis.

Brake Master Cylinder Leaking / Faulty

brake applied

Refer to this section.

Cruise Control Switch Faulty / Plug

Go to Pin Point Test D

Disconnected

Stop Lamp Switch Faulty / Plug

Go to Pin Point Test C

Disconnected

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