Code
C003C
HYUNDAI
C — Chassis
Rear Tone Wheel (Subfault)
Views:
UK: 19
EN: 19
RU: 25
AI status
Completed
Completed
100%
Causes
- Damaged or missing teeth on the rear tone/reluctor wheel
- Contamination on tone wheel or sensor (rust, metal debris, brake dust)
- Incorrect air gap or misalignment between sensor and tone wheel
- Faulty wheel speed sensor (Hall-effect or variable-reluctance)
- Open, shorted, or intermittent wiring/connectors to the sensor
- Excessive wheel bearing play or axle damage moving the tone wheel
Symptoms
- ABS warning light illuminated (often with ESC/traction control)
- Intermittent or no wheel speed reading for one rear wheel in scan tool
- Unexpected ABS/traction interventions or stability control faults
- Erratic speedometer or inconsistent wheel speed values
- Brake pulsation or degraded braking behavior under ABS events (rare)
What to check
- Read and record all ABS/ESC codes and freeze frame data with a capable scan tool
- Perform a visual inspection of the rear tone/reluctor ring for missing teeth, cracks, or heavy corrosion
- Inspect wheel hub and bearing for play or damage that could move the tone wheel
- Visually inspect sensor for damage, contamination, and proper mounting
- Inspect sensor connector for corrosion, bent pins, or water intrusion
- Backprobe sensor connector and monitor live wheel speed data while spinning the wheel
Signal parameters
- Sensor types: variable-reluctance (VR) or Hall-effect — consult vehicle service manual to confirm type
- VR sensor: produces AC sine waveform; amplitude increases with wheel speed (low-speed amplitudes often small — check with oscilloscope)
- Hall sensor: produces 0–Vref square wave (Vref typically 5V or vehicle logic level), frequency proportional to wheel speed; duty near 50% under ideal conditions
- Typical checks: continuity and sensor resistance (manufacturer spec required); AC output or square-wave presence must be verified with oscilloscope or scanner
- Air gap: small tolerance (often 0.5–3 mm) — exact spec available in the service manual
Diagnostic algorithm
- Connect scan tool, record C003C and any related codes, note freeze-frame data and live wheel speed readings.
- Clear codes, road test to see if C003C returns and to capture live data for the rear wheel sensors.
- Visually inspect the rear reluctor/tone wheel and sensor for physical damage, missing teeth, heavy rust, or contamination.
- Check wheel bearing and hub for axial/radial play that could move the tone wheel relative to the sensor.
- Inspect and clean the sensor and tone wheel area; verify sensor is securely mounted and not contacting the ring.
- Backprobe the sensor connector: verify reference voltage (for Hall), ground, and signal while cranking/wheel spin; check for intermittent by wiggling harness.
- Measure sensor resistance (if VR) and signal output while spinning the wheel: use oscilloscope for waveform quality or multimeter for AC output where applicable.
- Repair or replace damaged components: replace tone wheel or hub assembly if the ring is damaged, replace faulty sensor, repair wiring/connectors, or replace wheel bearing as required.
- After repairs, clear codes and perform a road test with live-data monitoring to confirm proper wheel speed signal and ensure C003C does not return.
Likely causes
- Reluctor ring has physical damage, missing teeth, or heavy corrosion
- Sensor damaged by impact, corrosion, or water ingress
- Connector corrosion or pin damage at the sensor/vehicle harness
- Sensor air gap out of specification (too large or contacting ring)
- Wiring chafed near suspension or wheel hub causing intermittent contact
Fault status
Status
C003C — Rear Tone Wheel (Subfault): Secondary fault detected in the rear wheel speed tone (reluctor) circuit. Possible causes include damaged reluctor ring, sensor failure, wiring/connectors, or misalignment. Inspect tone wheel, sensor, and wiring.
Repair difficulty: Medium
Diagnostic time: 1.0 - 2.5 hours
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