Electric Parking Brake System Description - Components
The electric parking brake system consists of the following primary components:
- VSA modulator-control unit
- Electric parking brake actuators
- Electric parking brake switch
- System indicator
For locations of each component on the vehicle, refer to Component Location Index , and for functions of the indicator, 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 actuator, increasing torque. The actuator turns the spindle and the adjuster nut inside the caliper piston force 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 four circuits, or the switch will be disabled and a DTC will be set.