brakes FORD MUSTANG 2003 Owner's Manual

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
152003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

PINPOINT TEST B: THE RED BRAKE WARNING INDICATOR IS
ALWAYS ON z
Is the alignment OK? A3 CHECK THE DISC BRAKE COMPONENTS
z
Check all disc brake calipers, anchor plate guide pins and
brake pads for binding, wear, damage, contamination and
correct installation.
z Are the disc brake calipers, anchor plate guide pins
and brake pads OK? Yes
GO to
A4 .
No
REPAIR or INSTALL new
components as necessary.
RETEST for normal
operation. A4 ROAD TEST THE VEHICLE
z
Road test the vehicle, and observe whether the drift
occurs with or without the brakes applied.
z Does the drift or pull occur with the brakes applied? Yes
REPAIR or INSTALL new
front disc brake caliper or
anchor plate guide pins on
the side opposite to the
direction of the drift or pull.
No
REPAIR or INSTALL new
front disc brake caliper or
anchor plate guide pins on
the side of the vehicle in the
direction of the drift or pull.
Test Step Result / Action to Take
B1 CHECK THE BRAKE MASTER CYLINDER FLUID
LEVEL SWITCH z
Key in OFF position.
z Disconnect: Brake Master Cylinder Fluid Level Switch
C124.
z Connect a fused jumper from C124- 2 circuit 977
(PK/WH) to C124- 3 circuit 128 (VT/YE). Yes
GO to
B2 .
No
INSTALL a new brake master Klj . 7 ba
152003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

The function of the power brake booster check valve is to allow manifold vacuum to enter the power
brake booster and prevent the escape of vacuum in case manifold vacuum is lost during sustained full
throttle operation.
To test the function of the power brake booster check valve :
zStart and run the engine for at least 10 seconds.
z Operate the brake pedal to check for power assist.
z Disconnect the vacuum booster hose from the power brake booster check valve. Do not remove
the power brake booster check valve from the power brake booster.
z There should be enough vacuum retained in the brake booster for at least one more power-
assisted brake operation.
Brake Master Cylinder — Normal Conditions
The following conditions are considered normal and are not indications that the brake master cylinder
is in need of service.
Condition 1: During normal operation of the brake master cylinder, the fluid level in the brake master
cylinder reservoir will rise during brake application and fall during release. The net fluid level (i.e., after
brake application and release) will remain unchanged.
Condition 2: A trace of brake fluid will exist on the booster shell below the master cylinder mounting
flange. This results from the normal lubricating action of the master cylinder bore and seal.
Condition 3: Fluid level will decrease with pad wear.
Brake Master Cylinder — Abnormal Conditions
Changes in brake pedal feel or travel are indicators that something could be wrong in the brake
system. GO to Symptom Chart for abnormal condition diagnosis.
Bypass Condition Test 1. Disconnect the brake lines at the brake master cylinder.
2. Plug the outlet ports of the brake master cylinder.
3. Apply the brakes. If brake pedal height cannot be maintained, the brake master cylinder has an internal leak and must be rebuilt or replaced.
Compensator Port Check
The purpose of the compensator ports in the brake master cylinder is to supply any additional brake
fluid required by the system due to brake pad wear and to allow brake fluid returning from the brake
lines to the brake master cylinder to enter the brake master cylinder reservoir.
The returning brake fluid will cause a slight turbulence in the brake master cylinder reservoir. Klj . 14 ba
152003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

GENERAL PROCEDURES
Hydraulic Leak Check
1. NOTE: Brake fluid is water soluble and it is possible that all evidence of fluid leakage has been
washed off if the vehicle has been operated in the rain or snow.
Make sure the brake master cylinder reservoir (2K478) is full.
2. Apply the brakes several times and make sure the brake pedal (2455) feel is not spongy. If necessary, bleed the system. For additional information, refer to Bleeding — System in this
section.
3. If the reservoir level is dropping, inspect the brake components, fittings and lines to locate the source of the leak.
SECTION 206-
00: Brake System — General Information 2003 Mustang Workshop Manual Klj . 1 ba
12003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

1.
CAUTION: Install the brake pads in full axle sets. Do not install new brake pads on
only one side of vehicle.
Install the new slipper and brake pads.
2. Position the caliper on the anchor plate and install the bolts.
3. Install the wheel and tire assembly. For additional information, refer to Section 204 - 04 .
4. Lower the vehicle.
5. WARNING: Use of any other than approved DOT 3 or DOT 4 brake fluid will cause
permanent damage to components and will render the brakes inoperative.
WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact
with eyes. Wash hands thoroughly after handling. If brake fluid contacts eyes, flush eyes
with running water for 15 minutes. Get medical attention if irritation persists. If taken
internally, drink water and induce vomiting. Get medical attention immediately.
CAUTION: Brake fluid is harmful to painted or plastic surfaces. If brake fluid is
spilled onto a painted or plastic surface, immediately wash it with water.
Check the fluid level at the master cylinder. Add fluid if necessary.
6. WARNING: Pump the brake pedal several times to make sure the caliper piston is
extended to its operating position. Failure to follow these instructions may result in
personal injury.
Verify correct brake operation. Klj . 3 ba
42003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

The dual brake system is split front and rear with the front wheel brakes comprising of one circuit and
the rear wheel brakes, the other circuit.
Brake Fluid
WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with
eyes. Wash hands thoroughly after handling. If brake fluid contacts eyes, flush with running
water for 15 minutes. Get medical attention if irritation persists. If taken internally, drink water
and induce vomiting. Get medical attention immediately.
Clean, fresh Ford High Performance DOT 3 Brake Fluid C6AZ-19542- AB or equivalent DOT 3 fluid
meeting Ford specification ESA- M6C25-A is the only brake fluid that should be used in Ford vehicles.
z Do not reuse brake fluid drained or bled from the system.
z Do not use brake fluid that has been stored in an open container.
z Do not mix different types of brake fluid.
Brake Master Cylinder
The brake master cylinder is a dual piston type. The brake master cylinder operates as follows: zWhen the brake pedal (2455) is depressed, pressure is applied by mechanical linkage to the
primary and secondary piston.
z Brake master cylinder pistons apply hydraulic pressure to the two hydraulic circuits.
z Brake master cylinder will not be overhauled, a new master cylinder is installed only.
The brake master cylinder consists of:
zbrake master cylinder reservoir (2K478)
z brake master cylinder body
Brake Master Cylinder Reservoir
NOTE: Whenever the brake master cylinder reservoir is removed from the brake master cylinder, new
grommets must be installed.
The brake master cylinder reservoir :
zis mounted to the brake master cylinder.
z holds fluid supply for each brake master cylinder hydraulic piston.
z provides visual fluid level markings.
z contains the brake master cylinder fluid level sensor. Klj . 2 ba
32003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

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
32003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

DESCRIPTION AND OPERATION
Brake Booster —
Hydro-Boost
The Hydro- Boost brake booster is a hydraulically operated brake booster powered by the power
steering pump (3A674). The power steering pump provides the fluid pressure to operate both the
power brake booster and the power steering gear (3504).
A Hydro- Boost reserve system (accumulator) stores sufficient fluid under pressure to provide at least
two power- assisted brake applications in the event the power steering pump fluid flow is interrupted.
For low assist concerns on vehicles equipped with the Hydro- Boost system, refer to Section 211 - 00 to
check the power steering pump pressure and flow.
The brakes can also be applied manually if the reserve system is depleted.
Any leakage goes directly back to the power steering pump reservoir (3E764). SECTION 206-
07: Power Brake Actuation 2003 Mustang Workshop Manual Item Part Number Description
1 2140 Master cylinder
2 2B559 Hydro-Boost Klj . 1 ba
22003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

z
Seized or heat
damaged
crankshaft main
bearing. z
INSTALL a new crankshaft main
bearing.
z Excessive
crankshaft end
play. z
INSTALL a new thrust bearing or
crankshaft (6303).
z Excessive
connecting rod
bearing clearance. z
INSTALL a new connecting rod
bearing or connecting rod
(6200).
z Heat damaged
connecting rod
bearing (6211). z
INSTALL a new connecting rod
bearing.
z Damaged
connecting rod
bushing (6207). z
INSTALL a new connecting rod
bushing.
z Worn cylinder. zREPAIR or INSTALL a new
cylinder block (6010).
z Worn piston (6108)
or piston pin
(6135). z
INSTALL a new piston or piston
pin.
z Damaged piston
rings. z
INSTALL new piston rings.
z Bent connecting
rod. z
INSTALL a new connecting rod.
z Malfunctioning
valve tappet (6500)
or lash adjuster. z
INSTALL a new valve tappet or
lash adjuster.
z Excessive valve
tappet or lash
adjuster clearance. z
ADJUST clearance or INSTALL
a new valve tappet guide or
valve tappet.
z Broken valve spring
(6513). z
INSTALL a new valve spring.
z Excessive valve
guide clearance. z
ADJUST clearance or INSTALL
a new valve guide (6510) or
valve.
z Insufficient
power z
Malfunctioning or
damaged ignition
system. z
Refer to the appropriate section
in Group 303 for the procedure.
REFER to the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual.
z Malfunctioning or
damaged fuel
system. z
Refer to the appropriate section
in Group 303 for the procedure.
REFER to the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual.
z Malfunctioning or
damaged air intake
system. z
Refer to the appropriate section
in Group 303 for the procedure.
REFER to the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual.
z Damaged or
plugged exhaust
system. z
INSPECT exhaust system.
z Incorrect tire size. zREFER to Section 204 - 04 .
z Dragging brakes. zREFER to Section 206 - 00 . Klj . 5 ba
172003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

DESCRIPTION AND OPERATION
Transmission Electronic Control System
The powertrain control module (PCM) and its input/output network control the following transmission
operations:
zShift timing
z Line pressure (shift feel)
z Torque converter clutch
The transmission control is separate from the engine control strategy in the PCM, although some of
the input signals are shared. When determining the best operating strategy for transmission operation,
the PCM uses input information from certain engine- related and driver-demand related sensors and
switches.
In addition, the PCM receives input signals from certain transmission- related sensors and switches.
The PCM also uses these signals when determining transmission operating strategy.
Using all of these input signals, the PCM can determine when the time and conditions are right for a
shift, or when to apply or release the torque converter clutch (TCC). It will also determine the best line
pressure needed to optimize shift feel. To accomplish this, the PCM uses hydraulic solenoids to control
transmission operation.
The following provides a brief description of each of the sensors and actuators used to control
transmission operation.
Powertrain Control Module (PCM)
The operation of the transmission is controlled by the powertrain control module (PCM). Many input
sensors provide information to the PCM. The PCM then controls actuators which determine
transmission operation.
Air Conditioning (A/C) Clutch
An electromagnetic clutch is energized when the clutch cycling pressure switch closes. The switch is
located on the suction accumulator/drier. The closing of the switch completes the circuit to the clutch
and draws it into engagement with the compressor driveshaft. When the A/C clutch is engaged,
electronic pressure control (EPC) is adjusted by the PCM to compensate for additional load on the
engine.
Brake Pedal Position (BPP) Switch
The brake pedal position (BPP) switch tells the PCM when the brakes are applied. The torque
converter clutch disengages when the brakes are applied. The BPP switch closes when the brakes are
applied and opens when they are released.
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor detects temperature of engine coolant and supplies the
information to the powertrain control module. The ECT sensor is used to control torque converter
clutch (TCC) operation. The ECT is installed in the heater outlet fitting or cooling passage on the
engine. For engine control applications, the ECT signal is used to modify ignition timing, EGR flow and
air- to-fuel ratio as a function of engine coolant temperature.
SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Klj . 1 ba
42003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_2748/S3B~us~en~ ...