C051500 - C051500 Right Rear Wheel Speed Sensor Signal Line Short to Power

DTC C051500: Diagnostic Report for Short Circuit Between Right Rear Wheel Speed Sensor Signal Line and Power Supply Line

Fault Depth Definition

DTC C051500 is defined as "Short Circuit Between Right Rear Wheel Speed Sensor Signal Line and Power Supply Line" in the vehicle electronic architecture. This fault code falls under the key monitoring scope of the Intelligent Power Brake System (IPB). In this technical context, "short circuit" does not refer to traditional ground short circuits but indicates unexpected electrical connectivity detected by the control unit between the right rear wheel speed sensor's signal output line and the power supply network.

This abnormal connectivity causes sensor signal voltage to rise to values close to the power rail, disrupting standard differential or pulse feedback logic. In the Intelligent Power Brake System, this fault code indicates that the vehicle's central processor (EPCU/Controller) cannot acquire real-time rotation speed information of the right rear wheel through correct analog-to-digital conversion. The system determines this as a serious electrical interference, thereby interrupting part of the ABS slip prevention control and ESC electronic stability system functional cycles based on wheel speed difference calculations to ensure overall vehicle operational safety is not excessively reduced in the presence of faults.

Common Fault Symptoms

When the vehicle control system records this DTC code, users may perceive the following specific phenomena through the instrument cluster or onboard information interaction system:

• Instrument Warning Light Abnormal Illumination: Due to partial failure of Intelligent Power Brake System functions, the Body Dynamic Control indicator light (e.g., ABS/ESP warning light) may remain on or display a fault status in a blinking mode.
• Active Safety Function Degradation: The vehicle enters a fault protection mode, causing the Anti-lock Braking System (ABS) and body posture stability control to be unable to perform closed-loop adjustments based on right rear wheel data.
• Missing Driver Assistance Feedback: In cases involving electronic power steering or active obstacle avoidance logic associated with braking conditions, the system may fail to intervene due to lack of accurate wheel speed data.
• Locked Historical Fault Record: The vehicle self-diagnosis system marks this abnormal event as a "Current DTC" and continuously triggers relevant logical judgments during driving.

Core Fault Cause Analysis

Based on the control unit's diagnostic logic, the root causes leading to electrical short circuits between signal lines and power supply lines are primarily summarized in the following three physical dimensions:

• Hardware Component Failure: Internal right rear wheel speed sensor failure. The sensor's encapsulation structure may be damaged, causing breakdown or leakage between its signal output pins and internal power management modules; alternatively, the sensor itself may fail due to electromagnetic interference shielding layer malfunction, leading external supply voltage coupling into the signal circuit.
• Wiring/Connector Physical Damage: Harness or connector failure. The connecting cables for the right rear wheel speed sensor have insulation layer damage, causing signal wires to contact nearby power wires during driving vibration (grounding to power); or the internal pins of the sensor plug deteriorate and corrode, leading to electrical isolation failure.
• Controller Logic Operation Abnormality: Intelligent Power Brake Controller Failure. Although rare, if the Analog-to-Digital Converter (ADC) sampling circuit within the controller experiences voltage reference drift or comparator threshold damage, it may misjudge signal levels as shorted states.

Technical Monitoring and Trigger Logic

The control unit's judgment of this fault follows a strict real-time monitoring process, its technical logic being:

• Operating Condition Restriction: The prerequisite condition for fault triggering is the ignition switch placed in the ON position. Only when the vehicle power management system completes initialization self-checks and the engine or high-voltage system is in standby status does the controller activate high-precision impedance measurement on the wheel speed sensor circuit.
• Monitoring Target Parameter: The control unit continuously monitors the signal line voltage waveform of the right rear wheel speed sensor and its potential difference with the power supply line. Normally, the signal line should maintain a specific baseline voltage range; if an abnormally high signal line voltage value is detected that converges with the power rail voltage, the system determines "Power Supply Short Circuit".
• Fault Judgment Threshold: When the controller confirms the signal line lacks expected impedance isolation characteristics within multiple sampling cycles (typically spanning specific engine speed or vehicle speed windows), the logic threshold is crossed. At this time, DTC C051500 is formally written into non-volatile memory, and relevant dashboard warning lights are illuminated until the code is cleared and the fault does not recur.