2003 FORD MUSTANG tire pressure

in the brake master cylinder reservoir are also indicators of system concerns.
If a wheel is locked and the vehicle must be moved, open a bleeder screw at the locked wheel (1007)
to let out enough fluid to relieve the pressure. Close the bleeder screw. This bleeding operation may
release the brakes but will not correct the cause of trouble. If this does not relieve the locked wheel
condition, repair the locked components before proceeding.
Inspect all hoses and connections. All unused vacuum connectors should be capped. Make sure
hoses and their connections are correctly secured and in good condition with no holes, soft or
collapsed areas.
Non-
Pressure Leaks
The only part of the brake system that could have a brake fluid loss that does not appear when the
system is under pressure is the brake master cylinder reservoir area. Brake fluid loss can be caused
by a missing or poorly- fitted brake master cylinder filler cap (2162), a punctured or otherwise damaged
brake master cylinder reservoir, a missing or damaged brake master cylinder filler cap gasket, or by
missing, damaged or poorly- fitted sealing grommets between the brake master cylinder (2140) and the
brake master cylinder reservoir.
The brake master cylinder reservoir grommets are not separately serviceable and must be installed
new as part of a new brake master cylinder reservoir.
Install a new flexible brake hose if it shows signs of softening, cracking or other damage.
When installing a new brake hose, position the hose to avoid contact with other vehicle components.
Road Test
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.
The driver should have a thorough knowledge of brake system operation and accepted general
performance guidelines in order to make good comparisons and detect performance problems.
Select a road that is reasonably smooth and level. Gravel or bumpy roads are not suitable because the
surface does not allow the tires to grip the road equally. Avoid crowned roads.
A key factor in evaluating brake concerns is the deceleration rate. This varies from vehicle to vehicle
and with changes in operating conditions. It is evident how well the brakes are working after just a few
applications.
Avoid locking the brakes. Locked brakes are not an indication of braking efficiency.
Visual Inspection Chart Mechanical Electrical
z
Brake master cylinder
z Brake caliper piston
z Brake discs
z Brake pads z
Parking brake switch
z Damaged or corroded wiring harness
z Brake master cylinder fluid level switch Klj . 2 ba
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For low or spongy brake pedal concerns:
zcheck and, if necessary, refill the brake master cylinder reservoir.
z bleed the brake system and retest the brake pedal feel.
z if the brake pedal is still low or feels spongy, check the brake pedal mounting for looseness and
correct installation. Check the power brake booster and the brake master cylinder for loose
mounting. Correct as necessary and retest the system for normal operation.
For a slow or incomplete brake pedal return concern:
zinspect for binding, damage, correct installation or interference at the brake pedal.
z check the power brake booster for binding, damage and correct installation.
Vibration When Brakes are Applied
For vibration concerns when brakes are applied, perform the following procedure.
Visually inspect: ztire condition and pressure.
z suspension bushings and ball joints.
Correct as necessary. 1. Verify and isolate the concern. Brake roughness can be felt in: zthe steering wheel.
z the seat.
z the brake pedal.
2. After verifying the concern, check for related concerns in the: zOn- Line Automotive Service Information System (OASIS).
z Technical Service Bulletins.
3. Check wheel bearing end- play and correct as necessary.
4. NOTE: Begin at the front of the vehicle unless the vibration has been isolated to the rear.
Remove the tire and wheel.
5. Remove the brake caliper.
6. Measure and record the brake disc thickness. Install a new brake disc if the thickness after machining will be at or below specification. The specification is molded into the brake disc. Do z
Power brake booster
z Brake pedal linkage
z Vacuum booster hose
z Tires
z Foreign material Klj . 3 ba
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not machine a new brake disc.
7. For vehicles with a two- piece hub and brake disc assembly:
z Match-mark before disassembly.
z Remove the brake disc.
z Using a die grinder with a mild abrasive (Scotch Brite® type), remove any rust or
corrosion from the hub and brake disc mounting surfaces.
z Align the match- marks and reinstall the brake disc on the hub.
8. CAUTION: Do not use a bench lathe to machine brake discs.
NOTE: The depth of cut must be between 0.10 and 0.20 mm (0.004 and 0.008 inch). Lighter
cuts will cause heat and wear. Heavier cuts will cause poor brake disc surface finish.
Using on- vehicle brake lathe, machine the brake discs. Follow the manufacturer's instructions.
After machining, make sure the brake disc still meets the thickness specification.
9. Using a dial indicator, verify that the brake disc lateral runout is now within vehicle specification.
10. Remove any metal chips.
11. Remove the hub adapter.
12. Remove any remaining metal chips from the machining operation.
13. CAUTION: Do not carry out this step on rear drum- in-hat brake discs.
For vehicles with a two- piece hub and a non drum- in-hat brake disc assembly:
z Remove the brake disc from the hub.
z Remove any remaining metal chips from hub and brake disc mounting surfaces and from
the ABS sensor.
z Apply High Temperature Nickel Anti- Seize Lubricant F6AZ-9L494-AA to the mounting
surfaces.
z Using the match- marks, mount the brake disc on the hub.
14. Install the caliper and check brake operation.
Symptom Chart Symptom Chart
Condition
Possible Sources Action
z The Brakes Pull or
Drift z
Tire air pressure.
z Wheel alignment.
z Brake pads.
z Brake components.
z Suspension
component. z
Go To Pinpoint Test A .
z The Red Brake
Warning Indicator Is z
Instrument cluster.
z Circuit. z
Go To Pinpoint Test B . Klj . 4 ba
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Pinpoint Tests
PINPOINT TEST A: THE BRAKES PULL OR DRIFT booster hose as
necessary.
z Red Brake Warning
Indicator Inoperative z
Circuit.
z Bulb. z
REFER to Section 413 -
01 .
z Brake Noise zDisc brake
component. z
MACHINE or INSTALL a
new brake component as
necessary. REFER to
Section 206 - 03 or
Section 206 - 04 .
z Hydro-Boost, No
Power Assist z
Power steering
pump.
z Linkage.
z Power steering
fluid flow.
z Hydro-boost unit. z
Go To Pinpoint Test E .
z Hydro-Boost Erratic
Operation, Sticks,
Binds or Grabs z
Supply hose.
z Hydro-boost unit. z
Go To Pinpoint Test F .
z Hydro-Boost Brake
System Operation
Suspect z
Leakage.
z Hydro-boost unit. z
Go To Pinpoint Test G .
Test Step Result / Action to Take
A1 CHECK THE TIRES
NOTE:
Check tire pressure with the brakes off.
z Check tires for uneven and excessive wear and for correct
pressure.
z Are the tires OK? Yes
GO to
A2 .
No
CORRECT as necessary.
RETEST for normal
operation. A2 CHECK THE ALIGNMENT
z
Check the caster, camber and toe. Refer to Section 204 -
00 . Yes
GO to
A3 .
No
CORRECT alignment as
necessary. REFER to Section 204 - 00 . RETEST for correct
operation. Klj . 6 ba
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PINPOINT TEST C: BRAKE LOCKUP DURING LIGHT BRAKE PEDAL
FORCE z
Is the resistance greater than 10,000 ohms? No
REPAIR the ground short in
circuit 128 (VT/YE). TEST the
system for normal operation.
B6 CHECK DAYTIME RUNNING LIGHTS (DRL) MODULE
z
Disconnect: DRL Module C1030.
z Measure the resistance to ground at C124- 2.
z Is the resistance greater than 10,000 ohms? Yes
REPAIR the DRL module. TEST
the system for normal operation.
No
REPAIR the ground short in
circuit 22 (LB/BK) or 977
(VT/WH). TEST the system for
normal operation.
Test Step Result / Action to Take
C1 INSPECT THE TIRES
z
Inspect the tires for uneven or excessive
wear, correct pressure, correct size and
type.
z Are the tires OK? Yes
GO to
C2 .
No
CORRECT as necessary. RETEST for
normal operation. C2 CHECK THE BRAKE CALIPER
COMPONENTS z
Inspect the brake pads and brake discs for
wear, damage, contamination and correct
installation.
z Are the brake components OK? Yes
GO to
C3 .
No
CORRECT as necessary. RETEST for
normal operation. C3 CHECK THE PROPORTIONING VALVE
z
Install the gauges from the ABS brake and
pressure test kit on one front and one rear
bleeder screw.
z Apply 6895 kPa (1000 psi) to the front
brake system.
z Is the pressure in the rear system 3516- Yes
INSPECT the disc brake calipers and
INSTALL new calipers as necessary.
RETEST for normal operation.
No Klj . 9 ba
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DESCRIPTION AND OPERATION
Hydraulic Brake Actuation
CAUTION: Blistering or swelling of rubber brake components may indicate contamination
of the brake fluid by a petroleum based substance. New rubber components must be installed
in the hydraulic brake system if contaminated and the entire hydraulic brake system must be
flushed with clean brake fluid to prevent recontamination.
This vehicle is equipped with a brake pedal actuated dual brake system. The system consists of the
following:
zpower brake booster (2005)
z brake master cylinder (2140)
z brake pressure control valve (2B091)
z disc brake calipers (2B120)
z rear disc brake calipers (2553)
z brake tubes and hoses
z anti- lock brake system (ABS) components
SECTION 206-
06: Hydraulic Brake Actuation 2003 Mustang Workshop Manual Item Part Number Description
1 2K478 Master cylinder reservoir
2 2140 Master cylinder
3 — Pedal support bracket (part of 2455)
4 2455 Brake pedal Klj . 1 ba
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Brake Pressure Control Valve
The brake pressure control valve proportions the pressure to the rear brakes.
zWhen the brake pedal is applied, brake fluid pressure passes through the proportioning valves
to the rear brake system until the valve split point is reached.
z Above its split point, the proportioning valve begins to reduce the hydraulic pressure to the rear
brakes, creating a balanced braking condition between the front and rear brakes.
Brake Tubes and Hoses CAUTION: Never use copper tubing. It is subject to fatigue, cracking and corrosion which
could result in brake tube failure.
Steel tubing is used throughout the brake hydraulic system. All brake tube fittings must be correctly
double flared to provide strong leakproof connections. When bending the tubing to fit the underbody or
rear axle contours, be careful not to kink or crack the tube.
If a section of brake tube is damaged, the entire section must be removed and a new tube of the same
type, size, shape and length installed.
When replacing hydraulic brake tubing, hoses, or connectors, tighten all connections securely. After
installation, bleed the brake system. For additional information, refer to Section 206 - 00 . Klj . 3 ba
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1. Verify the customer concern by operating the steering system.
2. Inspect Tires
zCheck the tire pressure. Refer to the Vehicle Certification (VC) label.
z Verify that all tires are sized to specification.
z Check the tires for damage or uneven wear.
3. Belt and Tensioner Check zRefer to Section 303 - 05 for diagnosis and testing of the accessory drive system.
4. Fluid Level Check zVerify that the power steering fluid level is within the appropriate indicated range, hot for
the 3.8L engine and cold for the 4.6L engine. Add Motorcraft MERCON® Multi- Purpose
ATF XT -2-QDX or MERCON® equivalent.
5. Air Bleeding zVerify that there is no air in the power steering system. Run the engine (6007) until it
reaches normal operating temperature. Turn the steering wheel to the left and right
several times without hitting the stops. If any air bubbles are present, refer to Purging —
CII Power Steering Pump or
Purging — CIII Power Steering Pump in this section.
External Leak Check — Typical Power Rack-and-Pinion Steering Gear Klj . 2 ba
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