Principles of Operation

Principles of Operation

Hydraulic Brake System
Applying the brake pedal uses lever action to push a rod into the brake booster which, through the use of vacuum, boosts the force of the rod and then transmits this force into the master cylinder. This produces hydraulic pressure in the master cylinder.

The hydraulic pressure is transmitted by brake fluid through the brake tubes to the ABS hydraulic control unit (HCU), which then distributes that pressure to the individual brake calipers. The brake calipers use the hydraulic pressure to apply the pads. The application of the brake pads will cause the rotation of the wheels to slow or stop depending on how much brake pressure is applied.

Brake System Warning Indicator
The red brake system warning indicator alerts the driver to certain conditions that exist in the brake system. The conditions are low brake fluid level, the parking brake is applied or a fault in the ABS (if the yellow ABS warning indicator is also illuminated).

When the fluid level in the master cylinder reservoir is below a predetermined level, the fluid level switch in the reservoir closes and grounds a circuit from the smart junction box (SJB). The SJB then sends a message to the instrument cluster via the high-speed controller area network (HS-CAN) bus to illuminate the red brake system warning indicator. When the parking brake is applied, the parking brake switch (located in the parking brake control) closes and grounds a circuit from the SJB. The SJB then sends a message to the instrument cluster via the HS-CAN bus to illuminate the red brake warning indicator.

When a DTC is set in the ABS module, the ABS module will send a message to the instrument cluster via the HS-CAN bus. The instrument cluster will then illuminate the red brake warning indicator and the yellow ABS warning indicator.

Adjustable Pedals
The brake and accelerator pedals can be adjusted for a more comfortable driving position. The adjustable pedals feature is operational with the ignition switch in the RUN, ACC or OFF position. Adjustable pedals may be connected to the driver memory system, if equipped, or they may be a stand alone system.

Non-Memory Adjustable Pedals
For non-memory adjustable pedals, the pedals are controlled directly by the adjustable pedal switch and motor. The motor is attached to the accelerator pedal and the brake pedal is connected to the motor via a cable. The motor is connected to the brake pedal and accelerator pedal and both move together as an assembly. The pedals are adjusted by pressing the adjustable pedal switch in either the forward or rearward position. Pressing the switch powers the adjustable pedal motor which then causes the pedals to move either toward the driver or away from the driver.

Memory Adjustable Pedals
For memory adjustable pedals, the pedals can be adjusted in 1 of 3 ways:
^ By pressing the adjustable pedal switch.
^ By pressing the memory position 1 or memory position 2 switch.
^ By using the remote transmitter.

For memory adjustable pedals, the pedals are controlled by the driver seat module (DSM). The DSM receives input from 1 of the 3 sources and then powers the adjustable pedal motor in the desired direction. The DSM will also control the driver seat position and the side-view mirror positions.

For information on setting and recalling a memory pedal position, refer to Memory Position Programming in Seats.