Electric Parking Brake System Description
Overview
The electric parking brake system replaces the traditional parking brake pedal or lever and linkage with an electrically controlled parking brake mechanism in the rear calipers. This reduces driver effort and provides additional features such as:
- Simple electric switch operation
- Parking brake release upon acceleration
- Automatic rollaway prevention
The system is controlled by the VSA modulator-control unit.
Function
The electric parking brake system has the following functions.
Manual Operating Function
The electric parking brake can be manually applied and released using the switch. Pulling up on the electric parking brake switch applies the parking brake. Firmly applying the brake pedal and pushing down on the electric parking brake switch release it.
Drive Away Assist Function
- A/T, CVT:
The electric parking brake is released automatically when the vehicle is driven away from a stop with the driver's seat belt buckled. Problems in the electric parking brake switch circuits do not affect this function.
- M/T:
The electric parking brake is released automatically when the vehicle is driven away from a stop with the engine running, the vehicle in gear, the clutch engaged, and the driver's seat belt buckled. When the electric parking brake control unit confirms the appropriate amount of engine torque to move the vehicle forward relative to the incline of the slope, the electric parking brake releases. Problems in the electric parking brake switch circuits do not affect this function.
External Applying Function
During automatic brake hold or low speed follow control, the electric parking brake operates automatically depending on a request.
Automatic Adjusting Function
Because the parking brake is automatically adjusted whenever applying the parking brake, the parking brake does not require adjustment. Additionally, if the vehicle is driven 1864 miles (3, 000 km) without applying the parking brake, the parking brake is automatically applied and released while the vehicle is in the OFF (LOCK) mode, and performs the automatic adjustment in order to compensate for brake pad wear.
Emergency Brake Function
In an emergency situation, such as a failure of the conventional brake system, the VSA system applies the emergency brake by activating the electric parking brake switch continuously. There are two controls depending on the state of the VSA system.
- In cases where the VSA system can perform the pressure adding control:
The electric parking brake system sends the brake control request to the VSA system which applies the emergency brake using the pressure adding control.
- In cases where the VSA system can not perform the pressure adding control:
The electric parking brake system controls the electric parking brake actuator so that the wheels do not lock, and applies the emergency brake instead of the VSA system. However, if wheel speed signal is abnormal, the anti-lock control will not function.
The Parking Brake Cannot Be Manually Released With The Ignition In The OFF Mode
In the ignition OFF (LOCK) mode, the system does not allow the manual release of the electric parking brake.
Ignition OFF Apply Function
The electric parking brake system can apply the parking brake automatically when the vehicle is turned to the OFF (LOCK) mode based on customer preferences. It may be necessary to temporarily cancel this function in certain service procedures. Refer to How to Temporarily Cancel Automatic Electric Parking Brake or How to Enter Neutral Position Holding Mode (A/T) . For more information on how to turn on or off the automatic parking brake function, refer to the owner's manual.
Ignition OFF Apply Function - Switch Failure (M/T)
If the electric parking brake switch has a fault, the system will automatically apply the parking brake when the vehicle is turned to the OFF(LOCK) mode.
Maintenance Mode
The electric parking brake system has a brake pad maintenance mode functional test. This test fully releases the parking brake mechanism so that brake service, such as rear pad replacement, can be done. Maintenance mode can be activated by the HDS.