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.
2006.0 Fiesta 1212006
procarmanuals.com
31 0-02B-3 Acceleration Control - 2.OL Duratec-HE (M14) 31 0-02B-3
DESCRIPTION AND OPERATION
position from the throttle position (TP) sensors to
make sure that the requested position has been
lachieved .
N0TE:Do not install a new accelerator pedal
unless a relevant accelerator pedal DTC has been
stored in the PCM. For additional information refer
to WDS.
The accelerator pedal is a non-serviceable
component which cannot be adjusted and therefore
must not be disassembled or tampered with.
The throttle body is directly controlled by the PCM
and has two TP sensors, TP
1 and TP 2. The TP
sensors output a voltage to the PCM that
corresponds to the actual throttle plate position.
When the throttle body motor is not being powered
up, the throttle plate sits open at approximately 8
degrees from the closed in-bore position. This
position (also referred to as the default position),
is maintained within the throttle body by two internal
compression return springs acting in opposing
directions, these springs are a non-serviceable
item.
The PCM continuously monitors both APP sensors
and both TP sensors to make sure that the system
,is functioning as expected. All acceleration control
( 'system concerns will be detected by the PCM and
the appropriate diagnostic trouble code (DTC) set.
The malfunction indicator lamp (MIL), located in
the instrument cluster will also be illuminated if a
concern is apparent. As the acceleration control
system is of a safety-critical nature, it is possible
that a system concern will result in a reduced
vehicle performance and a DTC stored in the PCM.
For additional information refer to WDS.
2006.0 Fiesta 1212006 G422706en
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