C0305

Code

HUMMER C — Chassis

Right Front Wheel Speed Sensor Circuit Malfunction

Brand: HUMMER

Type: C — Chassis

Views: UK: 8 EN: 12 RU: 8

AI status

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Page language: EN

Causes

Failed or damaged right front wheel speed sensor (magnetic or Hall-type)
Open, shorted or corroded wiring/connector at the sensor
Contaminated sensor (metal debris, oil, or rust) or damaged tone/ring reluctor
Damaged wheel bearing or hub causing sensor misalignment
Faulty ABS/traction control module or poor ground at module
Intermittent connection due to water ingress or bent pins

Symptoms

ABS warning lamp illuminated
Traction control / stability control warning lamp may also be on
Loss or intermittent operation of ABS and traction control
Possible inconsistent speedometer or drivability issues in vehicles that use wheel speed for control
Diagnostic trouble code stored for right front wheel sensor

What to check

Scan with an OEM-capable scan tool, record freeze frame and live data for right front wheel speed
Visually inspect sensor, connector and wiring for damage, corrosion, or contamination
Check connector pins for bent or pushed-out terminals and proper mating
Backprobe signal/ power/ground pins and wiggle harness while watching live data for dropouts
Measure sensor resistance (if passive) and compare to typical/vehicle spec
Measure AC voltage output while spinning wheel (passive) or check 0–5V square wave (active) with an oscilloscope or multimeter

Signal parameters

Passive (magnetic) sensor: AC voltage increases with speed; small AC volts at low speed (e.g., ~0.1–2 VAC at low speeds) and several volts at higher speeds (vehicle-specific)
Passive sensor resistance (typical range): roughly 500–2000 ohms (varies by design) — compare to OEM spec
Active (Hall/electronic) sensor: reference supply typically 5V (sometimes 12V), output is a square wave 0–5V relative to wheel speed
Typical output frequency: increases with wheel speed — tens to several hundred Hz depending on vehicle speed
Expected waveform: clean alternating waveform (passive) or stable square pulses (active) without dropouts, distortion or constant zero/constant voltage

Diagnostic algorithm

Read and record stored codes and freeze-frame data with a scan tool. Note whether other wheel speed codes are present.
Visually inspect right front sensor, harness and connector for damage, contamination or corrosion. Clean connector and re-seat.
With ignition on, backprobe connector to verify sensor power/reference and ground (for active sensors). Confirm reference voltage per OEM spec.
Measure sensor resistance at the connector (engine off). If passive, compare to spec. If open/infinite or shorted, replace sensor.
Spin the wheel and measure AC output (passive) or signal waveform (active) with an oscilloscope or multimeter. Look for increasing amplitude/frequency with speed and no dropouts.
Wiggle the wiring and connector while monitoring live data/signals to find intermittent opens or shorts.
Inspect tone ring/reluctor for damage, missing teeth, or excessive air gap. Repair/replace if damaged or misaligned.
Check wheel bearing/hub for excessive play that could change sensor gap and cause noise or intermittent signal.
If tests on sensor and wiring pass, check continuity between sensor connector and ABS module for shorts to ground or power and for proper resistance. Repair wiring as needed.
If wiring and sensor are good and problem persists, test or replace ABS module input circuit per OEM procedures or consult wiring diagrams/technical service bulletins.
Clear codes and test drive, re-scan to confirm the fault is resolved.

Likely causes

Damaged sensor or sensor connector (most common)
Wiring harness chafed or shorted near suspension or steering components
Reluctor (tone) ring damaged, missing teeth or covered in debris
Corroded connector or poor ground at ABS module
Module input circuit fault (less common)

Fault status

⚠️ Status

Right front wheel speed sensor circuit malfunction detected. ABS/traction control may be disabled; inspect right front wheel speed sensor, wiring, and tone ring.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.0 hours

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