Ford F150 Pickup. Instruction - part 337

Fig. 1: Brake System Description And Operation 
Courtesy of FORD MOTOR CO. 

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The vehicle is equipped with a vacuum-assisted power braking system. 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Brake System - General Information - F150 Pickup

  

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The braking system is a front-to-rear split hydraulic system.  

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The front brakes utilize a dual piston brake caliper and brake disc system.  

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The rear disc brakes utilize a single piston brake caliper and brake disc system.  

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The rear drum brakes use a self-adjusting system.  

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The optional rear disc parking brake system is a drum-in-hat parking brake system and is not self-
adjusting.  

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The rear anti-lock brake system (RABS) is standard equipment.  

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A 4-wheel anti-lock brake system (4WABS) is optional.  

Brake Fluid 

Use clean, fresh Ford High Performance DOT 3 Motor Vehicle Brake Fluid C6AZ-19542-AB or equivalent 
meeting Ford specification ESA-M6C25A. 

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Do not reuse brake fluid drained from the system.  

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Do not use brake fluid that has been stored in an open container.  

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Do not use contaminated brake fluid.  

DIAGNOSIS AND TESTING 

BRAKE SYSTEM 

Refer to SYSTEM WIRING DIAGRAMS - F150 for schematic and connector information. 

Inspection and Verification 

Preliminary Checks 

WARNING:

Use of any other than 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: 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.

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 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Brake System - General Information - F150 Pickup

  

The first indicator 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 in the brake master 
cylinder reservoir are also indicators of system concerns. 

If a wheel (1007) is locked and the vehicle must be moved, open a bleeder screw at the locked wheel 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. 

Brake Booster 

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, soft or collapsed areas. 

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 indicator of braking efficiency. 

Visual Inspection Chart 

VISUAL INSPECTION CHART 

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 certain that the brake warning 
indicator is functional. For additional information, refer to INSTRUMENT 
CLUSTER-CONVENTIONAL - F150 or to INSTRUMENT CLUSTER-NATURAL 
GAS - F150 .

Mechanical

Electrical

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Brake master cylinder  

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Brake caliper piston  

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Parking brake switch 

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Damaged or corroded wiring harness 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Brake System - General Information - F150 Pickup

  

Vibration When Brakes Are Applied 

For vibration concerns when brakes are applied, carry out the following procedure. 

1. Verify the concern. 

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Brake vibration concerns are caused by uneven disc wear or lining transfer and should be verified 
with a test drive since these conditions are difficult to measure with available shop tools. For 
additional information, refer to NOISE, VIBRATION & HARSHNESS - F150 PICKUP .  

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Check Technical Service Bulletins for vehicle specific brake concerns.  

2. Remove the wheel and tire assembly. For additional information, refer to WHEELS & TIRES - F150 

PICKUP .  

3. Remove the brake caliper. For additional information, refer to DISC & DRUM .  

4. Inspect the brake linings. Install new pads if the thickness of the lining is below the specification or if 

cracks in the lining wide enough to see through down to the backing plate are present.  

5. Inspect the brake discs. 

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Install new discs if cracked.  

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Resurface the brake discs if the diagnosis has revealed vibration in the steering wheel, seat, or pedal 
while braking. Heavily scored brake discs, similar to that caused by linings worn down to the 
backing plate, should also be machined.  

6. Measure the disc thickness and record the measurement. For discs that require machining, install a new 

disc if the thickness is less than 0.60 mm (0.02 in) above the minimum thickness specification cast in the 
disc. This will make sure that the disc will be above minimum thickness after machining. Do not machine 
new discs.  

7. For vehicles with a two-piece brake disc and hub assembly: 

1. Match-mark before disassembly.  

2. Remove the brake disc. 

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Brake discs  

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Wheel bearings  

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Brake pads  

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Brake shoes and linings  

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Brake drum  

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Power brake booster  

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Brake pedal linkage  

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Booster vacuum hose  

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Tires  

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Foreign material  

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Brake master cylinder fluid level switch 

CAUTION: Do not use an abrasive sanding disc since it will remove paint 

or other protective finishes from wheel and metal from 
mounting surfaces, adversely affecting corrosion protection 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Brake System - General Information - F150 Pickup