206-00-1 7 Brake System - General Information 206-00-1 7
DIAGNOSIS AND TESTING
TEST CONDITIONS DETAILSIRESU LTSIACTIONS
I D5: PERFORM A BRAKE MASTER CYLINDER BYPASS CONDITION CHECK
Test for a brake master cylinder bypass. REFER
to the component tests.
Was a concern found?
+ Yes
INSTALL a new brake master cylinder.
REFER to: (206-06 Hydraulic Brake Actuation)
Brake Master Cylinder
- RHD (Removal and
Installation),
Brake Master Cylinder
- LHD (Removal and
Installation). ADD fluid and BLEED the brake system.
REFER to: (206-00 Brake System
- General
Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General Procedures). TEST the system for normal operation.
+ No
System OK.
( 1 PINPOINT TEST E : PEDAL EASES DOWN SLOWLY
TEST CONDITIONS
DETAILSIRESULTSIACTIONS 1
I El: CHECK BRAKE PEDAL OPERATION 1
Check if the condition occurs when applying the
brake pedal while the vehicle is moving.
Does the condition occur with the vehicle
stationary?
+ Yes GO to E2.
-, No
REFER to the component tests.
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206-00-18 Brake System - General Information 206-00-1 8
DIAGNOSIS AND TESTING
TEST CONDITIONS DETAILSIRESU LTSIACTIONS
E2: CHECK FOR BRAKE SYSTEM LEAKS
Check for external brake system leaks. Refer
to the component tests.
Are any leaks found?
+ Yes
REPAIR as necessary. ADD fluid and BLEED
the brake system. REFER to: (206-00 Brake
System
- General Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General Procedures). TEST the system for normal operation.
+ No
GO to E3.
E3: PERFORM A BRAKE MASTER CYLINDER BYPASS TEST
Test for a brake master cylinder bypass. Refer
to the component tests.
Was a concern found?
+ Yes
INSTALL a new brake master cylinder.
REFER to: (206-06 Hydraulic Brake Actuation)
Brake Master Cylinder
- RHD (Removal and
Installation),
Brake Master Cylinder
- LHD (Removal and
Installation).
ADD fluid and BLEED the bake system.
REFER to: (206-00 Brake System
- General
Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General Procedures). TEST the system for normal operation.
-+ No
System
OK. TEST the system for normal
operation.
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206-00-1 9 Brake System - General Information 206-00-1 9
DIAGNOSIS AND TESTING
PINPOINT TEST F : PEDAL IS LOW OR FEELS SPONGY
TEST CONDITIONS
DETAILSIRESU LTSIACTIONS I I F1: ROAD TEST THE VEHICLE
rn Road test the vehicle and apply the foot brake.
Did the brake pedal feel spongy?
1 Ehicle OK.
I F2: CHECK BRAKE FLUID LEVEL I
rn Check the brake master cylinder reservoir fluid
level.
Is the fluid level OK?
-+ Yes
GO to F3.
-, No
CHECK the brake master cylinder reservoir
sealing points. REFER to the component tests.
ADD fluid and BLEED the brake system.
REFER to: (206-00 Brake System
- General
Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures). TEST the system for normal operation.
I F3: CHECK FILLER CAP VENT I
rn Check if the filler cap vent holes are clogged or
dirty.
Was a concern found?
-+ Yes
CLEAN as necessary. TEST the system for
normal operation.
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206-00-21 Brake System - General Information 206-00-21
DIAGNOSIS AND TESTING
TEST CONDITIONS DETAILSIRESU LTSIACTIONS
162: TIRE INSPECTION
rn Check for excessive tire wear or incorrect tire
pressures.
Are the tires in good order?
-+ Yes
GO to G3. GO to Pinpoint Test G.
-+ No
SUBSTITUTE known good tires. INFLATE to
the correct pressure. TEST the system for
normal operation.
163: BRAKE SHOES OR BRAKE PADS INSPECTION I
rn Inspect the brake shoes or brake pads are
correctly fitted and for grease or fluid contamin-
ation or wear concerns.
Are there any concerns?
-+ Yes
REPAIR or INSTALL new components as
necessary. TEST the system for normal
operation.
-+ No
GO to G4. GO to Pinpoint Test G.
1 64: CHECK PRESSURE CONSCIOUS REDUCING VALVE-RIGHT-HAND REAR I
rn Install pressure gauges in the left-hand front
and right-hand rear bleed nipples. Apply the brake to read 6895
kPa (1 000 psi) at the left-
hand front wheel.
- Read the pressure at the right-hand rear
wheel.
Does the pressure gauge read between 4692-
5164
kPa (680-750 psi) at the right-hand rear
wheel?
-+ Yes
TEST the brake booster. Go to Pinpoint Test
I.
-+ No
INSTALL a new right-hand rear brake pres-
sure control valve. BLEED the brake system.
REFER to: (206-00 Brake System
- General
Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures). TEST the system normal operation.
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206-00-26 Brake System - General Information 206-00-26
DIAGNOSIS AND TESTING
TEST CONDITIONS DETAILSIRESU LTSIACTIONS
I J6: CHECK BRAKE PEDAL LINKAGE If
rn Disconnect the actuator rod from the pedal pin
and apply the brake pedal fully.
Did the pedal move freely?
-+ Yes
GO to J7.
+ No
REPAIR or INSTALL new brake pedal bush-
ings. REFER to: (206-06 Hydraulic Brake
Actuation)
Brake Pedal
- LHD, Vehicles With: Manual
Transaxle (Removal and Installation),
Brake Pedal
- LHD, Vehicles With: 4-Speed
Automatic Transmission
(AW81-40), Vehicles
With: Automated Gearshift (Removal and
Installation),
Brake Pedal
- RHD (Removal and Installation).
TEST the system for normal operation.
157: CHECK BRAKE PRESSURE CONTROL VALVE I
rn Check the brake pressure control valve for
contamination.
Is the brake fluid contaminated?
+ Yes
INSTALL a new brake pressure control valve.
FILL the brake master cylinder reservoir.
BLEED the brake system. REFER to: (206-00
Brake System
- General Information)
1 Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures). TEST the system for normal operation.
1 * Ehicle OK.
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206-00-28 Brake System - General Information 206-00-28
DIAGNOSIS AND TESTING
PINPOINT TEST L : SLOW OR INCOMPLETE BRAKE PEDAL RETURN
TEST CONDITIONS
DETAILSIRESU LTSIACTIONS /"'
I L1: CHECK FOR BRAKE PEDAL RETURN I[<.
Run the engine at fast idle while making several
brake applications. Pull the brake pedal rear-
ward with approximately 44.5 N
(1 0 lbs) force.
Release the brake pedal and measure the
distance to the floor pan. Make a hard brake
application. Release the brake pedal and
measure the brake pedal to floor pan distance.
The brake pedal should return to its original
position.
Did the brake pedal return to its original posi-
tion?
+ Yes
Vehicle OK.
+ No
GO to L2.
I L2: CHECK FOR BRAKE PEDAL BINDING
1 171 Check the brake pedal for free operation.
I Is the brake pedal operating freely?
+ Yes
I INSTALL a new brake booster. REFER to:
(206-07 Power Brake Actuation)
Brake Booster
- LHD (Removal and lnstallation),
Brake Booster
- RHD (Removal and lnstallation).
TEST the system for normal operation.
+ No
REPAIR or INSTALL new brake pedal bush-
ings. REFER to: (206-06 Hydraulic Brake
Actuation)
Brake Pedal
- LHD, Vehicles With: Manual
Transaxle (Removal and lnstallation),
Brake Pedal
- LHD, Vehicles With: 4-Speed
Automatic Transmission
(AW81-40), Vehicles
With: Automated Gearshift (Removal and
Installation),
Brake Pedal
- RHD (Removal and lnstallation).
TEST the system for normal operation.
Component Tests It is possible that all evidence of fluid leakage may
have washed off if the vehicle has been operated
in rain or snow, as brake fluid is water-soluble.
Hydraulic Leak Check Refill the system, bleed then apply the brakes
several times. Examine the system to verify that
NOTE:Thet-e is a common clutch and brake fluid
the reservoir fluid level is actually dropping. Locate
reservoir, therefore it is possible that a clutch leak
can lead to reduction in the reservoir level.
-- --
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206-00-29 Brake System - General Information 206-00-29
DIAGNOSIS AND TESTING
and repair the external leak. If the fluid level drops
and no external leak can be found, check for a
brake master cylinder bore end seal leak.
Brake System Check
Brake Pedal Reserve Check
Where a low brake pedal or the feel of a
bottomed-out condition exists, check for brake
pedal reserve.
1. Operate the engine at idle with the transaxle in
NEUTRAL.
2. Apply the brake pedal lightly three or four times.
3. Allow 15 seconds for vacuum to replenish the
brake booster.
N0TE:This increased resistance may feel like
something has bottomed out.
4. Apply the brake pedal until it stops moving
downward or an increased resistance to the
pedal travel occurs.
5. Hold the brake pedal in the applied position and
raise the engine speed to approximately 2000
rpm.
N0TE:The additional movement of the brake pedal
is the result of the increased engine intake manifold
vacuum which exerts more force on the brake
booster during engine rundown. This means that
additional stroke is available in the brake master
cylinder and the brake system is not bottoming out.
6. Release the accelerator pedal and observe that
the brake pedal moves downward as the engine
returns to idle speed.
Brake Booster Functional Test
lnspect all hoses and connections. All unused
vacuum connectors should be capped. Hoses and
their connections should be correctly secured and
in good condition with no holes and no collapsed 2.
With the transaxle in NEUTRAL, stop the engine
and apply the parking brake. Apply the brake
pedal several times to exhaust all vacuum in
the system.
3. With the engine turned off and all vacuum in the
system exhausted, apply the brake pedal and hold it down. Start the engine. If the vacuum
system is operating, the brake pedal will tend
to move downward under constant foot
pressure. If no motion is felt, the vacuum
booster system is not functioning.
4. Remove the vacuum hose from the brake
booster.
Intake manifold vacuum should be
available at the brake booster end of the hose
with the engine at idle speed and the transaxle
in NEUTRAL. Make sure that all unused vacuum
outlets are correctly capped, hose connectors
are correctly secured and vacuum hoses are in
good condition. When it is established that
manifold vacuum is available to the brake
booster, connector the vacuum hose to the
brake booster and repeat Step
3. If no
downward movement of the brake pedal is felt,
install a new brake booster. REFER to: (206-07
Power Brake Actuation)
Brake Booster
- LHD (Removal and lnstallation),
Brake Booster
- RHD (Removal and lnstallation).
5. Operate the engine a minimum of 10 seconds
at fast idle. Stop the engine and let the vehicle
stand for
10 minutes. Then, apply the brake
pedal with approximately 89
N (20 lb) force. The
pedal feel (brake application) should be the
same as that noted with the engine operating.
If the brake pedal feels hard (no power assist),
install a new vacuum check valve and then
repeat the test. If the brake pedal still feels hard,
install a new brake booster. REFER to: (206-07
Power Brake Actuation)
Brake Booster
- LHD (Removal and Installation),
Brake Booster
- RHD e em oval and installation).
If the brake pedal movement feels spongy, bleed
the brake system. REFER to: (206-00 Brake
System
- General Information)
areas. Inspect the check valve on the brake booster Brake System Bleeding (General Procedures),
for damage. Brake
System Pressure Bleeding (General
Procedures).
Brake Booster Operation Check
Brake Master Cylinder
1. Check the hydraulic brake system for leaks or
low fluid. Usually,
the first and strongest indicator of anything
wrong with the braking system is a feeling through
the brake pedal. In diagnosing the condition of the
brake master cylinder, check pedal feel as
2006.0 Fiesta 1212006 G28494en I
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Brake System - General Information
DIAGNOSIS AND TESTING
evidence of a brake concern. Check for the brake
warning indicator illumination and the fluid level in
the master cylinder reservoir.
Normal Conditions
The following conditions are considered normal
and are not indications that the brake master
cylinder is in need of service.
- Modern brake systems are not designed to
produce as hard a pedal effort as in the past.
Complaints of light pedal efforts should be
compared to pedal efforts of another vehicle, of
the same model and year.
- During normal operation of the brake the fluid
level in the reservoir will rise during brake
application and fall during release. The net fluid
level
(i.e., after brake application and release)
will remain unchanged.
- A trace of brake fluid will exists on the brake
booster shell below the master cylinder
mounting flange. This results from the normal
lubricating action of the master cylinder bore
end seal.
- The fluid level will fall with brake shoe and lining
wear.
Abnormal Conditions
N0TE:Prior to performing any diagnosis, make
sure the brake system warning indicator is
functional.
Changes in brake pedal feel or travel are indicators
that something could be wrong with the braking system. The diagnostic procedure and techniques
use brake pedal feel, warning indicator illumination
and low brake fluid level as indicators in diagnosing
braking system concerns. The following conditions
are considered abnormal and indicate that the
brake master cylinder is in need of service.
- The brake pedal effort is excessive. This may
be caused by a bind or obstruction in the pedal
.
or linkage, clogged fluid control valve or ( ' insufficient booster vacuum.
- The rear brakes lock up during light pedal force.
This may be caused by incorrect tire pressures,
grease or fluid on the brake shoes and linings,
damaged brake shoes and linings, incorrectly
adjusted parking brake, or damaged or
contaminated brake pressure control valves.
- The brake pedal effort is erratic. This condition
could be caused by a brake booster malfunction,
extreme caliper piston knock back or incorrectly
installed brake shoes and linings.
- The brake warning indicator is ON. This may
be caused by low fluid level, ignition wire routing
too close to the fluid level indicator assembly,
or float assembly damage.
Bypass Condition Test
1. Check the fluid in brake master cylinder. Fill the
brake master cylinder reservoir if low or empty.
2. Observe the fluid level in the brake master
cylinder reservoir. If after several brake
applications, the fluid level remains the same,
measure the wheel turning torque required to
rotate the wheels with the brakes applied as
follows:
Place the transaxle in NEUTRAL and raise and
support the vehicle. REFER to: (1 00-02 Jacking
and Lifting)
Jacking (Description and Operation),
Lifting (Description and Operation).
Apply the brakes with a minimum of 445 N (100
Ib) and hold for approximately 15 seconds. With
the brakes still applied, exert a torque on the front
wheels of 10.1 Nm (75
1b.R). If either wheel rotates,
install a new brake master cylinder. REFER to:
(206-06 Hydraulic Brake Actuation)
- The brake pedal goes down fast. This could be Brake Master Cylinder - RHD (Removal and
caused by an external or internal leak. Installation),
- The brake
pedal eases down slowly. This could Brake Master Cylinder - LHD
(Removal and
be caused by an external or internal leak. Installation).
- The
brake pedal is low and or feels spongy. This
condition may be caused by no fluid in the brake
Non-Pressure Leaks master cylinder reservoir, reservoir cap vent
holes clogged or air in the hydraulic system.
Any empty brake master cylinder reservoir
condition may be caused by two types of
non-pressure external leaks.
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