Electric Parking Brake System Description - Components
Components
The electric parking brake system consists of the following primary components:
- VSA modulator-control unit
- Electric parking brake actuators
- Electric parking brake switch
- Clutch pedal stroke sensor (M/T)
- System indicator
For locations of each component on the vehicle, refer to Component Location Index , and for indicator functions, refer to How to Troubleshoot the Electric Parking Brake .
Electric Parking Brake Actuator
The electric parking brake actuator has a built-in DC motor. When the motor operates, the motor's speed is reduced by the 2 step worm gear reducer and a ball screw mechanism, increasing torque. The 2nd worm wheel gear turns the spindle and the nut inside the caliper piston forcing it outward to generate brake pad clamping force. The electric parking brake actuators are automatically adjusted to compensate for brake pad wear, so no parking brake adjustment is necessary.
When the electric parking brake system has a malfunction and the parking brake cannot be released, you can release the parking brake by doing the forced cancellation procedure. Refer to the forced cancellation procedure .
Electric Parking Brake Switch
The electric parking brake switch is connected to the VSA modulator-control unit using four separate circuits. The control unit must see the correct voltage patterns on all 4 circuits, or the switch will be disabled and a DTC will be set.
Clutch Pedal Stroke Sensor (M/T)
The clutch pedal stroke sensor is located in the clutch pedal assembly. The clutch pedal stroke sensor detects the stroke of clutch pedal, and outputs two kinds of voltage values depending on the given angle. The VSA modulator-control unit determines the clutch engagement status from the clutch pedal stroke sensor.In addition, the VSA modulator-control unit sends the clutch pedal stroke sensor value to the PCM via F-CAN.
Clutch pedal stroke sensor zero point learning (M/T):
The VSA modulator-control unit learns the clutch pedal stroke sensor position when the clutch pedal is fully released. This learning is automatically performed when the ignition switch is turned on without pressing the clutch pedal after you do any of these actions:
- Replacing the VSA modulator-control unit.
- Replacing the clutch pedal stroke sensor.
Clutch engagement point learning (M/T)
The clutch engagement point learning is necessary to release the parking brake in an appropriate timing when the drive away assist function operates.When starting the vehicle, the learning is automatically performed based on the clutch pedal position signal, the engine speed signal, and the accelerator pedal position signal. The VSA modulator-control unit learns the clutch pedal position value by calculating the value from the engine speed changing rate when the accelerator pedal signal is lower than the determined threshold. This learning is performed several times whenever the ignition switch is turned on.