Hydraulic System: Description and Operation
Hydraulic Brake Actuation
Hydraulic Brake Actuation
The hydraulic brake actuation system consists of the following components:
- Brake master cylinder and fluid reservoir
- Brake tubes and hoses
- Brake pedal and bracket
- Hydraulic Control Unit (HCU)
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 forced through the brake tubes and flexible hoses to the HCU. The brake fluid is then distributed to the front and rear brake calipers. The fluid enters the caliper, forcing the caliper pistons and brake pads outward against the brake disc friction surface. When the brake pedal is released, brake fluid pressure is relieved, returning the front and rear brake caliper pistons and brake pads to the unapplied position.
For information on the HCU, refer to Vehicle Dynamic Systems Description and Operation.
Adjustable Pedals
Adjustable brake and accelerator pedals are available as an optional feature on this vehicle. The brake pedal position can be changed in phase with the accelerator pedal to increase driver comfort. Two different adjustable pedal systems are available; one that is connected to the memory feature option and one that is not connected to the memory feature option.
Without Memory Feature
Adjustable brake pedals without memory feature consist of the following components:
- Adjustable brake pedal and bracket
- Adjustable accelerator pedal and bracket, refer to Acceleration Control Acceleration Control
- Adjustable pedal switch
- Adjustable pedal motor
- Adjustable pedal cables
The pedals are adjusted through the use of a rocker switch mounted on the instrument panel. One end of the motor is connected directly to the accelerator pedal and the other end is connected to the brake pedal through a cable and worm gear. When the motor is energized, both the motor and the cable spin to adjust the pedals either forward (away from the driver) or rearward (toward the driver) depending on how the switch is pressed.
With Memory Feature
Adjustable brake pedals with memory feature consist of the same components as a system without memory feature with the following additional components:
- Driver Seat Module (DSM), refer to Seating Description and Operation.
- Memory SET switch, refer to Seating Description and Operation.
- Remote Keyless Entry (RKE) transmitter, refer to Handles, Locks, Latches and Entry Systems Description and Operation.
The pedals on a system with memory feature can be adjusted through the use of a rocker switch (mounted on the instrument panel), the memory SET switch (driver door panel) or the RKE transmitter. When a switch is pressed or the transmitter is activated, a signal is sent to the DSM. The DSM then sends voltage to the adjustable pedal motor which operates in the same manner as the system without memory feature.