2007 FORD FIESTA brakes

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Page 175 of 1226

FORD FIESTA 2007 Workshop Manual
206-00-3 Brake System - General Information 206-00-3
DIAGNOSIS AND TESTING
Brake System
The brakes system operates by transferring effort
applied to the brake pedal by the driver to the
br

206-00-3 Brake System - General Information 206-00-3
DIAGNOSIS AND TESTING
Brake System
The brakes system operates by transferring effort
applied to the brake pedal by the driver to the
brakes at each wheel.
The braking effort is distributed to each wheel,
using a hydraulic system. The system is assisted
using a vacuum brake booster that reduces pedal
effort and increases hydraulic pressure.
The parking brake operates on the rear wheels
and is applied using a hand operated control.
lnspection and Verification
N0TE:Before carrying out any diagnosis, make
sure that the brake system warning indicator is
functional.
1. Verify the customer concern.
2. Visually inspect for obvious signs of mechanical
damage.
3. If an obvious cause for an observed or reported
concern is found, correct the case (if possible)
before proceeding to the next step.
4. If the cause if not visually evident, verify the
symptom and refer to the Symptom Chart.
Visual lnspection Chart
Road Test
1.
Perform a road test to compare actual vehicle
braking performance with the performance
standards expected by the driver. The ability of the
test driver to make valid comparisons and detect
performance deficiencies will depend on
experience.
Mechanical
- Tire pressure
- Wheels and tires
- Fluid leak from brake line(s)
The driver should have a thorough knowledge of
the brake system operation and accepted general
performance guidelines to make good comparisons
, and detect performance concerns.
An experienced technician will always establish a
route that will be used for all brake diagnosis road
tests. The road selected will be reasonably smooth and level. Gravel
or bumpy roads are not suitable
because the surface does not allow the tires to grip
the road equally. Crowned roads should be avoided
because of the large amount of weight shifted to
the low set of wheels on this type of road. Once
the route is established and consistently used, the
road surface variable can be eliminated from the
test results.
Before a road test, get a complete description of
the customer concerns or suspected condition.
From the description, the technician will be able to
match possible causes with symptoms. Certain
components will be identified as possible sources
while others will be eliminated by the evidence.
More importantly, the customer description can
reveal unsafe conditions which should be checked
or corrected before a road test. The description will
also help form the basic approach to the road test
by narrowing the concern to specific components,
vehicle speed or conditions.
Begin the road test with a general brake
performance check. Using the description of the
concern, test the brakes at different vehicle speeds
using both light and heavy pedal pressure.
Determine if the concern is in the front or rear
braking system. First use the foot brake and then
the parking brake. If the condition
(i.e. pull,
vibration, pulsation) occurs only on operation of
the parking brake, the concern is in the rear brake
system.
If the condition occurs when the foot brake
is depressed, the concern is in the front brake
system.
Avoid locking the brakes and sliding the tires. This
condition will not indicate brake efficiency. A heavily
braked but turning wheel will stop the vehicle in a
shorter distance than locked wheels.
If the concern becomes evident during this check,
make sure it fits the description given before the
road test. If the concern is not evident, attempt to
duplicate the condition using the information from
the description.
If a concern exists, use the Brake System Symptom
Chart in order to isolate it to a specific sub-system
and condition description. From this description, a
list of possible sources can be used to further
narrow the cause to a specific component or
condition.
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2006.0 Fiesta 1212006 G28494en
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