C11B113 - C11B113 Right Caliper Motor Circuit Fault (Open Circuit)

Fault Depth Definition

DTC C11B113 belongs to the architecture of the Electronic Parking Brake System (EPBS), representing a diagnostic identification for the status of the right rear wheel caliper motor circuit. The triggering of this fault code implies that when the control unit (ECU/Controller) performs command monitoring, it detects an "Open Circuit" state in the wiring connected to the right caliper motor. At the technical level, this indicates a physical interruption in either the signal feedback loop or power transmission loop between the actuator and the controller, preventing the system from establishing an effective electrical pathway to complete the transmission of mechanical braking actions. This definition clarifies that the fault is not limited to a single component but involves logical determination of current path integrity by the control strategy.

Common Fault Symptoms

When the system determines an open circuit fault in this wiring, the vehicle driving status will present the following perceptible abnormal feedback:

• Loss of Right Parking Brake Function: After the driver operates the electronic parking switch, the right caliper motor cannot output sufficient braking torque, resulting in the parking mechanism not fully locking.
• Dashboard Warning Light Illumination: The on-board diagnostic system uploads the fault signal to the instrument panel, usually accompanied by the EPBS warning light illuminating or flashing, prompting the driver that the braking status is unreliable.
• Reduced Parking Holding Ability: After the vehicle stops, it may fail to maintain a static state on horizontal road surfaces, posing a risk of rolling away, and some models may experience situations where the right caliper cannot release or uneven braking force distribution occurs.

Core Fault Cause Analysis

Based on system architecture and circuit principles, the root causes of this fault code can be categorized into hardware or logic anomalies in the following three dimensions:

• Hardware Components (Right Rear Caliper Motor): As a physical actuator, an internal coil breakage, damaged drive chip, or open rotor in the right caliper motor leads to current inability to pass through, directly causing the control unit to detect signal interruption.
• Wiring and Connectors: The wire harness connecting the electronic parking controller with the right rear caliper may have a broken wire, terminal pin pull-out, connector corrosion, or looseness, causing physical disconnection and forming a high impedance open circuit state.
• Controller (Electronic Parking Controller): As the logic operation center of the system, internal power transistor failure on the output end responsible for driving the right motor or signal detection circuit abnormalities in the control unit may lead to misjudgment of the wiring status or inability to correctly drive the circuit closure.

Technical Monitoring and Trigger Logic

The generation of this fault code depends on real-time monitoring of circuit continuity by the control unit under specific operating conditions:

• Monitoring Target: The system continuously monitors the electrical continuity of the power supply loop and feedback loop of the right caliper motor, focusing on identifying open circuit states (high resistance or no current path).
• Trigger Operating Conditions: Fault determination is only effective when the following logic chain is met: Ignition switch in ON position, and the electronic parking switch is pulled up or pressed, at which point the system enters active monitoring mode.
• Logic Determination Mechanism: When the control unit issues a drive command, if an interruption of loop current signal or voltage state not matching expected closed-loop characteristics (i.e., open circuit characteristics) is detected, the system will record fault data streams and illuminate the fault light while freezing relevant functions to ensure driving safety.