Electric Parking Brake (EPB)

Description and Operation

Description

Description of EPB: EPB is the electronic parking brake. The EPB differs from existing parking brake systems that operate with a brake pedal or lever type. The EPB system sends a signal to the ECU when the driver operates the EPB switch. The ECU controls the EPB actuator, which consists of a gear and motor. The EPB performs several functions.

• Static Application
• Emergency braking function in case of hydraulic brake failure
• Self-Application

EPB Function

1. 1
   Parking Brake Switch Operation (Static Parking)

   • Manually apply the parking brake by pressing the EPB switch.
   • When the ignition switch is ON, the parking brake is applied with a clamping force reduced to less than 8% of the slope.
   • Except for the case above, the full clamping force is always applied.
2. 2
   Parking Brake Switch Release (Static Release)

   • Release the parking brake manually. The EPB is released.
   • For safety, it releases only when the ignition switch is ON and the brake pedal is depressed.
3. 3
   Dynamic Emergency Braking (Dynamic Braking)

   • Electronic Control Deceleration (ECD): When the EPB switch is pressed during driving, a request is sent to the VDC only when the hydraulic braking operation with the VDC is performed, not with EPB actuation.
   • Rear Wheel Unlock (RWU): If the VDC does not operate normally (VDC malfunction) when the EPB switch is operated during driving, and if wheel speed information can be obtained, the EPB actuator independently maintains safe vehicle movement and applies braking only while the switch is operated.
   • Slow Acceleration (SRU): If the VDC does not operate normally (VDC malfunction) when the EPB switch is operated during driving, and if wheel speed information cannot be obtained, the EPB automatically increases the parking force and gradually applies braking only while the switch is pressed.
4. 4
   Automatic EPB Application (Auto Apply)

   • When the vehicle is stopped with the Auto Hold (AVH) switch ON, the EPB is applied automatically when the engine is stopped.
5. 5
   Automatic EPB Forced Release (Drive Release)

   • The parking brake is released automatically when the accelerator pedal is depressed with the EPB applied.
   • For safety, automatic release occurs only when all of the following conditions are met:

   1. Engine running
   2. The seat belt is fastened.
   3. Driver's door, trunk and hood are closed.

   • To prevent the vehicle from rolling down the slope, it is released automatically only when the torque is above a certain level based on the slope.
6. 6
   Re-Apply EPB Force When Vehicle Rolls Back (Roll-Back Tightening)

   • Additional EPB force is generated when the vehicle moves forward. The bottom of the vehicle is detected after EPB force is applied.
   • With the engine off, this function is activated only when wheel speed information can be obtained (within 3 minutes after engine shutdown).
7. 7
   P to X (Automatic EPB Force Release for Speed Change): When the shift lever is moved from P or N to D or R, the parking brake is released automatically. However, this is possible only when the engine is running and the brake pedal is depressed, to ensure safe automatic release.
8. 8
   Auto Hold keeps the vehicle stationary by applying the hydraulic brake while the vehicle is at a standstill.

   1. Operating Condition
      • Engine is running
      • The Auto Hold switch is ON.
      • Driver's door, hood and trunk must be closed.
      • Driver seat belt fastened
      • Shift position is not in P range.
      • Vehicle stopped condition with brake pedal activated.
   2. (2) The Auto Hold function keeps the vehicle in the stopped state for no more than 10 minutes. The VDC valve maintains the stopped state by blocking the oil passage when the brake pedal is depressed.
   3. (3) Total Auto Hold operating time: 30 minutes maximum
   4. (4) Automatic Release Function: Auto Hold mode is canceled when the driver depresses the accelerator pedal in D/S/R range to start.
   5. (5) Automatically converts Auto Hold to EPB. Auto Hold automatically converts to EPB operation if one of the conditions below is met. [Normal Conversion Condition]
      • If the driver's door is opened and the driver's seat belt is released at the same time.
      • If the hood is open when the shift lever is in D or S.
      • If the trunk is open when the shift lever is in P.
      • In case of upper limit of Auto Hold operation: 10 minutes
      • Stopped on a 25° slope

   [Abnormal Conversion Condition]

   • When vehicle movement is detected.
   • When an ESP hydraulic system error is detected.

Warning Light

1. 1
   EPB Warning Light: The EPB warning light indicates its release and malfunction. The EPB warning light illuminates in the following cases.

   1. The EPB warning light illuminates once for 3 seconds when the ignition switch is turned ON. If the EPB system operates properly, the EPB warning light goes off.
   2. If the EPB system does not operate properly, the warning light illuminates. The EPB warning light comes on.
   3. The EPB warning light illuminates in diagnostic mode.
2. 2
   2. AUTO HOLD Function Indicator / AUTO HOLD Indicator

   1. AUTO HOLD switch ON: A. The brake system operates automatically when vehicle speed is "0" during parking or waiting at a red light, during braking (AUTO HOLD indicator: Green). B. The brake system is automatically released when the accelerator pedal is depressed. (AUTO HOLD indicator: White)
   2. AUTO HOLD switch OFF: AUTO HOLD does not operate.

Components and Component Location

COMPONENTS

1. Electronic Stability Program (ESP) Control Module 2. EPB Switch

3. Electronic Parking Brake (EPB) Actuator

Circuit Diagrams

Schematic Diagrams

TERMINAL FUNCTION

Pin No.	Function	Pin No.	Function
6	EPB Signal 1	2	Motor Ground ZR
5	EPB Signal 2	3	Motor Power RR
8	EPB Signal 3	12	Motor Ground RL
9	EPB Signal 4	13	Motor Power RL