Code
C1227
HUMMER
C — Chassis
Left Rear Excessive Wheel Speed Variation
Views:
UK: 5
EN: 25
RU: 11
AI status
Completed
Completed
100%
Causes
- Faulty or intermittent left‑rear wheel speed sensor (Hall or VR type)
- Damaged, missing or contaminated reluctor/tone ring or reluctor teeth
- Damaged wiring, corroded connector, poor pin contact or intermittent open/short to sensor
- Excessive play in wheel bearing or hub allowing sensor/tone ring misalignment
- Debris, rust, or brake dust on the sensor face
- Poor ground or power supply to the sensor
Symptoms
- ABS warning lamp illuminated
- Traction/stability control warning or reduced functionality
- Intermittent or unexpected ABS/TC activation while driving
- Diagnostic trouble code C1227 stored in ABS control module
- Possible pulsation or noise from affected wheel at speed if bearing/tone ring damaged
What to check
- Read ABS module codes and freeze‑frame data with a capable scan tool; capture raw wheel speed sensor data at rest and during wheel rotation
- Visually inspect left‑rear wheel area: sensor, tone ring, wheel bearing/hub, axle and brake components for damage or contamination
- Inspect and reseat the left‑rear sensor connector; check for corrosion, bent pins or water ingress
- Measure sensor resistance (if applicable) and compare to OEM spec; check for open/short
- Backprobe sensor signal while spinning wheel (jack/hoist) and observe waveform/frequency on scope or scan tool live data
- Wiggle wiring harness and connector while watching live data for intermittent changes
Signal parameters
- Hall/active sensors: digital square wave switching between reference voltage and ground; amplitude typically 0–5 V (or vehicle supply level) and frequency proportional to wheel speed
- Variable reluctance (VR) sensors: AC waveform with amplitude and frequency increasing with wheel speed (tens to hundreds of mV at low speed up to >1 V at higher speeds)
- Expected behavior: left‑rear wheel speed waveform/frequency should match other wheels proportionally; no sudden dropouts or large amplitude variation
- Resistance: sensor resistance should be within the manufacturer’s spec (check service manual) — open or short indicates sensor fault
- Continuity: good continuity from sensor connector to ABS module pin; no high resistance in ground or power supply
Diagnostic algorithm
- Verify: Connect a scan tool, read C1227 and any related codes. Note freeze frame and live wheel speed values.
- Compare Signals: With vehicle safely raised and in neutral, spin each wheel and compare left‑rear wheel speed signal to others using a scope or scan tool. Look for missing pulses, low amplitude, noise or dropouts.
- Visual Inspection: Inspect left‑rear sensor mounting, tone ring condition, sensor gap, presence of metal debris, rust, or physical damage. Check wheel bearing and hub for play.
- Connector/Harness: Unplug left‑rear sensor connector, inspect for corrosion, bent pins, water, or damaged insulation. Wiggle harness while monitoring signal for intermittent faults.
- Electrical Tests: Measure sensor resistance (if specified) and supply voltage/ground at connector. For VR sensors, measure AC voltage while spinning wheel. Repair if readings are out of spec.
- Repair/Replace: Clean sensor and tone ring if contaminated. Replace sensor if open, shorted, or signal remains erratic. Repair wiring or connector faults. Replace damaged reluctor/tone ring or hub/bearing if required.
- Clear & Test: Clear codes, perform a road test and watch live wheel speed signals during drive. Confirm ABS/TC lamps remain off and no recurrence of C1227.
- Module/Calibration: If wiring, sensor and tone ring check good and fault persists, verify ABS module grounds, power and software; consult manufacturer service procedures for module testing or reprogramming.
Likely causes
- Sensor contaminated or physically damaged
- Wiring harness chafed at suspension/wheel area or connector corroded
- Reluctor ring cracked, bent, missing teeth or covered with rust/metallic debris
- Wheel bearing/hub wear causing sensor gap variation
- Connector pin pushed out or poor crimp leading to intermittent signal
Fault status
Status
Left Rear wheel speed sensor signal varies excessively compared with other wheels. ABS/traction control performance may be affected. Inspect left‑rear sensor, tone ring, wiring, and hub/bearing.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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Code
C1227
HYUNDAI
C — Chassis
Throttle Valve Assembly
Views:
UK: 12
EN: 31
RU: 19
AI status
Completed
Completed
100%
Causes
- Faulty or intermittent left‑rear wheel speed sensor (Hall or VR type)
- Damaged, missing or contaminated reluctor/tone ring or reluctor teeth
- Damaged wiring, corroded connector, poor pin contact or intermittent open/short to sensor
- Excessive play in wheel bearing or hub allowing sensor/tone ring misalignment
- Debris, rust, or brake dust on the sensor face
- Poor ground or power supply to the sensor
Symptoms
- ABS warning lamp illuminated
- Traction/stability control warning or reduced functionality
- Intermittent or unexpected ABS/TC activation while driving
- Diagnostic trouble code C1227 stored in ABS control module
- Possible pulsation or noise from affected wheel at speed if bearing/tone ring damaged
What to check
- Read ABS module codes and freeze‑frame data with a capable scan tool; capture raw wheel speed sensor data at rest and during wheel rotation
- Visually inspect left‑rear wheel area: sensor, tone ring, wheel bearing/hub, axle and brake components for damage or contamination
- Inspect and reseat the left‑rear sensor connector; check for corrosion, bent pins or water ingress
- Measure sensor resistance (if applicable) and compare to OEM spec; check for open/short
- Backprobe sensor signal while spinning wheel (jack/hoist) and observe waveform/frequency on scope or scan tool live data
- Wiggle wiring harness and connector while watching live data for intermittent changes
Signal parameters
- Hall/active sensors: digital square wave switching between reference voltage and ground; amplitude typically 0–5 V (or vehicle supply level) and frequency proportional to wheel speed
- Variable reluctance (VR) sensors: AC waveform with amplitude and frequency increasing with wheel speed (tens to hundreds of mV at low speed up to >1 V at higher speeds)
- Expected behavior: left‑rear wheel speed waveform/frequency should match other wheels proportionally; no sudden dropouts or large amplitude variation
- Resistance: sensor resistance should be within the manufacturer’s spec (check service manual) — open or short indicates sensor fault
- Continuity: good continuity from sensor connector to ABS module pin; no high resistance in ground or power supply
Diagnostic algorithm
- Verify: Connect a scan tool, read C1227 and any related codes. Note freeze frame and live wheel speed values.
- Compare Signals: With vehicle safely raised and in neutral, spin each wheel and compare left‑rear wheel speed signal to others using a scope or scan tool. Look for missing pulses, low amplitude, noise or dropouts.
- Visual Inspection: Inspect left‑rear sensor mounting, tone ring condition, sensor gap, presence of metal debris, rust, or physical damage. Check wheel bearing and hub for play.
- Connector/Harness: Unplug left‑rear sensor connector, inspect for corrosion, bent pins, water, or damaged insulation. Wiggle harness while monitoring signal for intermittent faults.
- Electrical Tests: Measure sensor resistance (if specified) and supply voltage/ground at connector. For VR sensors, measure AC voltage while spinning wheel. Repair if readings are out of spec.
- Repair/Replace: Clean sensor and tone ring if contaminated. Replace sensor if open, shorted, or signal remains erratic. Repair wiring or connector faults. Replace damaged reluctor/tone ring or hub/bearing if required.
- Clear & Test: Clear codes, perform a road test and watch live wheel speed signals during drive. Confirm ABS/TC lamps remain off and no recurrence of C1227.
- Module/Calibration: If wiring, sensor and tone ring check good and fault persists, verify ABS module grounds, power and software; consult manufacturer service procedures for module testing or reprogramming.
Likely causes
- Sensor contaminated or physically damaged
- Wiring harness chafed at suspension/wheel area or connector corroded
- Reluctor ring cracked, bent, missing teeth or covered with rust/metallic debris
- Wheel bearing/hub wear causing sensor gap variation
- Connector pin pushed out or poor crimp leading to intermittent signal
Fault status
Status
Left Rear wheel speed sensor signal varies excessively compared with other wheels. ABS/traction control performance may be affected. Inspect left‑rear sensor, tone ring, wiring, and hub/bearing.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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Code
C1227
Other
C — Chassis
Speed Wheel Sensor LR Input Short Circuit To Battery
Views:
UK: 19
EN: 46
RU: 27
AI status
Completed
Completed
100%
Causes
- Faulty or intermittent left‑rear wheel speed sensor (Hall or VR type)
- Damaged, missing or contaminated reluctor/tone ring or reluctor teeth
- Damaged wiring, corroded connector, poor pin contact or intermittent open/short to sensor
- Excessive play in wheel bearing or hub allowing sensor/tone ring misalignment
- Debris, rust, or brake dust on the sensor face
- Poor ground or power supply to the sensor
Symptoms
- ABS warning lamp illuminated
- Traction/stability control warning or reduced functionality
- Intermittent or unexpected ABS/TC activation while driving
- Diagnostic trouble code C1227 stored in ABS control module
- Possible pulsation or noise from affected wheel at speed if bearing/tone ring damaged
What to check
- Read ABS module codes and freeze‑frame data with a capable scan tool; capture raw wheel speed sensor data at rest and during wheel rotation
- Visually inspect left‑rear wheel area: sensor, tone ring, wheel bearing/hub, axle and brake components for damage or contamination
- Inspect and reseat the left‑rear sensor connector; check for corrosion, bent pins or water ingress
- Measure sensor resistance (if applicable) and compare to OEM spec; check for open/short
- Backprobe sensor signal while spinning wheel (jack/hoist) and observe waveform/frequency on scope or scan tool live data
- Wiggle wiring harness and connector while watching live data for intermittent changes
Signal parameters
- Hall/active sensors: digital square wave switching between reference voltage and ground; amplitude typically 0–5 V (or vehicle supply level) and frequency proportional to wheel speed
- Variable reluctance (VR) sensors: AC waveform with amplitude and frequency increasing with wheel speed (tens to hundreds of mV at low speed up to >1 V at higher speeds)
- Expected behavior: left‑rear wheel speed waveform/frequency should match other wheels proportionally; no sudden dropouts or large amplitude variation
- Resistance: sensor resistance should be within the manufacturer’s spec (check service manual) — open or short indicates sensor fault
- Continuity: good continuity from sensor connector to ABS module pin; no high resistance in ground or power supply
Diagnostic algorithm
- Verify: Connect a scan tool, read C1227 and any related codes. Note freeze frame and live wheel speed values.
- Compare Signals: With vehicle safely raised and in neutral, spin each wheel and compare left‑rear wheel speed signal to others using a scope or scan tool. Look for missing pulses, low amplitude, noise or dropouts.
- Visual Inspection: Inspect left‑rear sensor mounting, tone ring condition, sensor gap, presence of metal debris, rust, or physical damage. Check wheel bearing and hub for play.
- Connector/Harness: Unplug left‑rear sensor connector, inspect for corrosion, bent pins, water, or damaged insulation. Wiggle harness while monitoring signal for intermittent faults.
- Electrical Tests: Measure sensor resistance (if specified) and supply voltage/ground at connector. For VR sensors, measure AC voltage while spinning wheel. Repair if readings are out of spec.
- Repair/Replace: Clean sensor and tone ring if contaminated. Replace sensor if open, shorted, or signal remains erratic. Repair wiring or connector faults. Replace damaged reluctor/tone ring or hub/bearing if required.
- Clear & Test: Clear codes, perform a road test and watch live wheel speed signals during drive. Confirm ABS/TC lamps remain off and no recurrence of C1227.
- Module/Calibration: If wiring, sensor and tone ring check good and fault persists, verify ABS module grounds, power and software; consult manufacturer service procedures for module testing or reprogramming.
Likely causes
- Sensor contaminated or physically damaged
- Wiring harness chafed at suspension/wheel area or connector corroded
- Reluctor ring cracked, bent, missing teeth or covered with rust/metallic debris
- Wheel bearing/hub wear causing sensor gap variation
- Connector pin pushed out or poor crimp leading to intermittent signal
Fault status
Status
Left Rear wheel speed sensor signal varies excessively compared with other wheels. ABS/traction control performance may be affected. Inspect left‑rear sensor, tone ring, wiring, and hub/bearing.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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