C003B00 - C003B00 Right Rear Wheel Speed Sensor Supply Voltage Low

Fault Depth Definition

C003B00 Right Rear Wheel Speed Sensor Supply Voltage Low, this DTC indicates that the Intelligent Power Brake System has detected an abnormality in the power supply voltage connected to the wheel speed sensor on the right rear wheel. In the vehicle's electronic control architecture, the wheel speed sensor is the terminal end of the reaction feedback loop, responsible for real-time feedback of physical position and rotation speed information to the main control unit. When the system judges "low supply voltage", it means the reference voltage or excitation voltage allocated by the control unit to that sensor has not reached the normal working threshold, causing signal acquisition link interruption or communication silence state. This fault directly affects the integrity of brake assist and safety stability functions and belongs to the electrical diagnostic category of key safety systems.

Common Fault Symptoms

When partial function failure of the Intelligent Power Brake System is triggered, the vehicle exhibits a series of perceptible driving feedbacks and instrument information:

• Dashboard Warning Light On: ABS (Anti-lock Braking System) indicator light on the dashboard or ESP/VCU system indicator lights stay on continuously or flash.
• Brake Assist Limited: Electronic parking brake systems or emergency braking enhancement features may be temporarily disabled due to missing sensor data, affecting short-distance stopping effect.
• Driving Mode Switching Limited: Energy recovery or coast control strategies of some vehicles will automatically downgrade to a safe operation mode.

Core Fault Cause Analysis

Based on technical principles and electrical logic, classify this fault into three dimensions of potential hardware or signal source issues:

• Hardware Component Failure (Sensor Unit): Aging internal circuitry inside the right rear wheel speed sensor, coil failure of magnetic induction or Hall element drift, causing it to be unable to stably maintain received voltage.
• Wiring and Connector Physical Connection: The harness or connector is defective, specifically manifesting as power supply signal line ground short, connector pin corrosion leading to excessive contact resistance, or harness wear causing signal reference point voltage drop.
• Controller Internal Logic Operation: Intelligent Power Brake Controller internal power management module output abnormality, or its software logic unable to correctly maintain the baseline power supply level at the sensor end.

Technical Monitoring and Trigger Logic

Fault code generation is based on control unit's real-time digital monitoring of electrical parameters:

• Monitoring Target: The control system continuously monitors the value relative to ground for the power supply terminal voltage (Supply Voltage) of the right rear wheel speed sensor.
• Judgment Condition: When vehicle ignition switch is in ON position, and during system self-check phase or dynamic operation, if sensor supply voltage is detected to be continuously below preset minimum value, enter fault storage logic.
• Trigger Mechanism: The control unit confirms this low voltage state is not transient fluctuation after validation, then writes DTC C003B00 into memory based on internal threshold logic, and prompts it during next ignition cycle. This process is strictly limited to system initialization phase after ignition switch turned ON and subsequent dynamic monitoring period.