brake fluid FORD MUSTANG 2003 User Guide

DIAGNOSIS AND TESTING
Brake System
Refer to Wiring Diagrams Cell
60 , Instrument Cluster for schematic and connector information.
Refer to Wiring Diagrams Cell 97 , Daytime Running Lamps for schematic and connector information.
Inspection and Verification WARNING: Use of any other than the approved DOT 3 brake fluid will cause permanent
damage to brake 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: Do not spill brake fluid onto painted surfaces. If spilled, wipe up immediately.
NOTE: Always check the fluid level in the brake master cylinder reservoir (2K478) before performing
the test procedures. If the fluid level is not at the correct level, add High Performance DOT 3 Brake
Fluid C6AZ- 19542-AB or equivalent DOT 3 fluid meeting Ford specification ESA- M6C25-A.
NOTE: Prior to performing any diagnosis, make sure the brake warning indicator is functional. For
additional information, refer to Section 413 - 01 .
The first indication that something may be wrong in the brake system is a change in the feeling through
the brake pedal (2455). The brake warning indicator in the instrument cluster and the brake fluid level SECTION 206-
00: Brake System — General Information 2003 Mustang Workshop Manual Special Tool(s)
73 Digital Multimeter
105-
R0051 or Equivalent ABS Brake and Pressure Test
Kit
107-
02350 or Equivalent Tire and Wheel Runout Gauge
Set
134-
00199 or Equivalent Klj . 1 ba
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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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Always On
zParking brake.
z Brake fluid level.
z Vibration When
Brakes Are Applied z
Rear disc brakes.
z Front disc brakes. z
REFER to Section 100 -
04 .
z Brake Pedal Goes
Down Fast z
Brake fluid level. zFILL the brake master
cylinder reservoir.
BLEED the system.
z Air in system. zBLEED the system.
z Brake master
cylinder. z
PERFORM the brake
master cylinder
component test in this
section.
z The Brake Pedal
Eases Down Slowly z
Air in system. zBLEED the system.
REFER to Bleeding —
System in this section.
z Brake master
cylinder. z
PERFORM the brake
master cylinder
component test in this
section.
z Brake Lockup During
Light Brake Pedal
Force z
Disc brake
component.
z Parking brake
component.
z Anti- lock brake
control system. z
Go To Pinpoint Test C .
z Excessive/Erratic
Brake Pedal Travel z
Leak in hydraulic
system.
z Air in system.
z Disc brake caliper.
z Brake master
cylinder. z
Go To Pinpoint Test D .
z Brakes Drag zParking brake
component. z
REPAIR or INSTALL new
components as
necessary. REFER to
Section 206 - 05 .
z Disc brake caliper. zREPAIR or INSTALL a
new brake caliper as
necessary. REFER to
Section 206 - 03 and
Section 206 - 04 .
z Brake booster-to-
brake master
cylinder push rod
adjustment. z
ADJUST the push rod.
REFER to Section 206 -
07 .
z Brake master
cylinder. z
PERFORM the brake
master cylinder
component test in this
section.
z Excessive Brake
Pedal Effort z
Power brake
booster. z
PERFORM the brake
booster component test
in this section.
z Power brake
booster check
valve (2365). z
PERFORM the check
valve component test in
this section.
z Power brake
booster hose. z
REROUTE, REPAIR or
INSTALL a new brake Klj . 5 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 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
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PINPOINT TEST D: EXCESSIVE/ERRATIC BRAKE PEDAL TRAVEL
PINPOINT TEST E: HYDRO-
BOOST, NO POWER ASSIST 4481 kPa (510-
650 psi)? INSTALL a new proportioning valve.
RETEST for normal operation.
Test Step Result / Action to Take
D1 CHECK FOR SPONGY PEDAL
z
Key in ON position.
z Operate the brake pedal and note pedal feel.
z Does the pedal feel spongy? Yes
BLEED the brake system. REFER to
Bleeding —
System in this section.
RETEST for normal operation.
No
GO to D2 .
D2 CHECK THE BRAKE PEDAL
z
Inspect the brake pedal and bracket for
binding, obstruction or damage.
z Is the brake pedal OK? Yes
GO to
D3 .
No
REPAIR or INSTALL a new brake pedal as
necessary. RETEST for normal operation. D3 CHECK THE BRAKE COMPONENTS
z
Inspect the calipers bolts, anchor plate bolts
and anti- rattle springs for binding, damage,
contamination and correct installation.
z Are the bolts and springs OK? Yes
GO to
D4 .
No
REPAIR or INSTALL new components as
necessary. RETEST for normal operation. D4 CHECK THE BOOSTER AND MASTER
CYLINDER z
Check the power brake booster and brake
master cylinder for correct installation and
correct push rod adjustment. Refer to
Section 206 - 06 and to Section 206 - 07 .
z Are the power brake booster and the
brake master cylinder OK? Yes
INSPECT the front wheel bearings for
wear, damage and correct installation and
the rear axle end play. CORRECT as
necessary. RETEST for normal operation.
No
CORRECT as necessary. RETEST for
normal operation.
Test Step Result / Action to Take
E1 CHECK FLUID LEVEL IN POWER STEERING
PUMP z
Check fluid level in power steering pump.
z Is level within specification? Yes
GO to
E2 .
No
CHECK for leakage of power steering
fluid. ADD fluid as necessary. E2 CHECK ACCESSORY DRIVE BELT Klj . 10 ba
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PINPOINT TEST F: HYDRO-
BOOST ERRATIC OPERATION, STICKS,
BINDS OR GRABS z
Check accessory drive belt tension and
condition. Refer to Section 303 - 05 .
z Is the accessory drive belt OK? Yes
GO to
E3 .
No
INSTALL a new accessory drive belt.
REFER to Section 303 - 05 .
E3 CHECK POWER STEERING HOSES
z
Check power steering pressure hoses, power
steering gear pressure hoses and power
steering return hose for cracks or leaks.
z Do power steering pressure hose, power
steering gear hose and power steering
return hose check OK? Yes
GO to
E4 .
No
INSTALL new hoses as necessary.
REFER to Section 211 - 00 .
E4 CHECK BRAKE PEDAL LINKAGE
z
Check brake pedal linkage for binding or
sticking operation.
z Does pedal linkage check OK? Yes
GO to
E5 .
No
INSTALL new pedal linkage as necessary.
REFER to Section 206 - 06 .
E5 CHECK POWER STEERING PUMP SPEED
z
Check engine idle speed against
specifications.
z Is engine idle speed OK? Yes
GO to
E6 .
No
SET engine idle speed to specification.
REFER to Powertrain Control/Emissions
Diagnosis (PC/ED) manual. E6 CHECK FOR PLUGGED RETURN HOSE
z
NOTE: The return hose from the oil cooler to
the power steering reservoir has an in- line
filter in the hose.
z Disconnect power steering return hose from
power steering fluid cooler and power
steering pump reservoir.
z Pass air through hose from the oil cooler end.
z Is hose plugged? Yes
INSTALL a new power steering return
hose.
No
GO to
E7 .
E7 CHECK POWER STEERING PUMP FLOW
AND RELIEF z
Test power steering pump for correct flow
and relief pressure. Refer to Section 211 - 00 .
z Is power steering pump operating
correctly? Yes
INSTALL a new power brake hydro-
boost
unit. REFER to Section 206 - 07 .
No
INSTALL a new power steering pump.
REFER to Section 211 - 02 .
Test Step Result / Action to
Take F1 CHECK SUPPLY HOSE
z
Check for obstructions in power steering return hose and Yes Klj . 11 ba
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PINPOINT TEST G: HYDRO-
BOOST BRAKE SYSTEM OPERATION
SUSPECT connections between the power steering pump reservoir and
between the power steering pump reservoir and the hydro-
boost
power brake booster.
z Are there any obstructions? REMOVE
obstructions or
INSTALL a new
hose.
No
GO to
F2 .
F2 CHECK BOOSTER OPERATION
z
Have an assistant check the fluid in the power steering pump
reservoir while rapidly applying the brake pedal approximately one
inch.
z Does the fluid show any movement or spouting? Yes
System OK.
No
INSTALL a new
hydro-boost
assembly. Test Step Result / Action to Take
G1 CHECK BASIC OPERATION
z
Key in OFF position.
z Press and release brake pedal several times to deplete all
hydraulic pressure from the hydro- boost power brake
booster.
z Press and hold brake pedal with light pressure.
z Key in START position.
z Does the brake pedal fall slightly and hold, and is less
pressure now required to hold brake pedal at the new
position? Yes
Hydro-
boost is OK.
No
GO to G2 .
G2 CHECK FOR HYDRAULIC BRAKE LEAK
z
With engine running, press and release brake pedal several
times.
z Hold brake pedal down with medium pressure, 34- 47 Nm
(25- 35 lb- ft).
z Does brake pedal move toward floor? Yes
GO to
G3 .
No
GO to G4 .
G3 CHECK FOR LEAKS —
BRAKE FLUID LINES z
Check for leaks at brake lines, including brake master
cylinder and brake hose.
z Do components check OK? Yes
COMPLETE master cylinder
By-
Pass Condition Test in
this section.
No
INSTALL new hoses and
lines as necessary. G4 CHECK HYDRO-
BOOST CONNECTIONS z
Clean the hydro- boost power brake booster, power steering
pressure hose, power steering gear pressure hose and
power steering return hose and connection.
z Start engine and run at idle.
z Check hose connections for leakage.
z Do hose connections check OK? Yes
GO to
G5 .
No
REPAIR or INSTALL new
hose and connections as
necessary. G5 CHECK FOR HYDRO-
BOOST LEAK Klj . 12 ba
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Component Tests
Brake Booster
1. Check the hydraulic brake system for leaks or insufficient fluid.
2. With the transmission (7003) in NEUTRAL, stop the engine (6007) and apply the parking brake control (2780). Apply the brake pedal several times to exhaust all vacuum in the system.
3. Apply the brake pedal and hold it in the applied position. 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 power brake booster system is not functioning. Continue with the following
steps.
4. Remove the vacuum booster hose from the check valve connection. Manifold vacuum must be available at the check valve end of the vacuum booster hose with the engine at idle speed and
the transmission in NEUTRAL. If the manifold vacuum is available to the power brake booster,
connect the vacuum booster hose to the power brake booster check valve and repeat Steps 2
and 3.
5. If no downward movement of the brake pedal is felt, install a new power brake booster.
6. 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 (20 lb) of force. The
brake pedal feel should be the same as that noted with the engine operating. If the brake pedal
feels hard (no power assist), install a new power brake booster check valve and retest. If the
brake pedal feels spongy, bleed the hydraulic system to remove air. For additional information,
refer to Bleeding — System in this section. Check Valve z
Engine running at idle speed.
z CAUTION: Do not hold the brake pedal at 444 Nm
(100 lb) force for more than 5 seconds at a time.
z Apply brake pedal with approximately 444 Nm (100 lb)
force and hold.
z Check hydro-boost unit input seal, housing seal,
accumulator seal, piston seal and spool plug seal for
leakage.
z Is hydro- boost unit free of leaks? Yes
GO to
G6 .
No
INSTALL a new hydro- boost
unit. G6 CHECK RESERVE RETENTION
z
Engine running at idle speed.
z CAUTION: Do not hold the brake pedal at 444 Nm
(100 lb) force for more than 5 seconds at a time.
z Charge system to pressure by holding the steering wheel at
stop or by pressing the brake pedal with approximately 444
Nm (100 lb) force.
z Key in OFF position.
z Wait five seconds.
z Press brake pedal and observe if there is any power brake
reserve.
z Is there any power brake reserve? Yes
Hydro-
boost unit is OK.
No
INSTALL a new hydro- boost
unit. Klj . 13 ba
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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
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