Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Brake System
The brake system consists of the following components:
- ABS hydraulic control unit (HCU)
- Vacuum booster power booster (E-150 to E-350 single rear wheel [SRW])
- Hydro-Boost® power booster (E-350 and E-450 dual rear wheel [DRW])
- Master cylinder
- Front brake discs
- Rear brake discs
- Parking brakes
The brake pedal is connected to the power brake booster, which is connected to the brake master cylinder. When the brake pedal is pressed, brake fluid is pushed through the doubled-walled steel tubes and flexible hoses to the front and rear disc brake calipers. The brake fluid enters the disc brake calipers, forcing the caliper pistons and brake pads outward against the brake disc friction surface, slowing or stopping rotation. When the brake pedal is released, brake fluid pressure is relieved, returning the front and rear disc brake caliper pistons and brake pads to the unapplied position.
For information on:
- the brake pedal, refer to HYDRAULIC BRAKE ACTUATION article.
- ABS and HCU, refer to VEHICLE DYNAMIC SYSTEMS article.
- the master cylinder and fluid reservoir, refer to HYDRAULIC BRAKE ACTUATION article.
- The brake power assist is vacuum-operated on the E-150, E-250 and E-350 SRW. The E-350 and E-450 DRW are equipped with a Hydro-Boost® power brake booster powered by the power steering pump. Refer to POWER BRAKE ACTUATION article.
- the front brake calipers, refer to FRONT DISC BRAKE article.
- the rear brake calipers, refer to REAR DISC BRAKE article.
- the drum-in-hat integrated parking brake system, refer to PARKING BRAKE AND ACTUATION article.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.