Ford 2002 Bantam, Руководство по ремонту

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206-00-17 Brake System — General Information 206-00-17
DIAGNOSIS AND TESTING ( CONTINUED )
E1092 EN 07/2001 2002 Bantam
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.
NOTE:
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.
NOTE:
The additional movement of the brake
pedal is the result of the increased engine
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
Inspect 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 areas. Inspect the check valve on
the brake booster for damage.
Brake Booster Operation Check
1. Check the hydraulic brake system for leaks
or low fluid.
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. 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.
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. 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. If the brake pedal movement feels
spongy, bleed the brake system.
REFER to
Section 206-06.
Brake Master Cylinder
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 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