Code
C0473
HUMMER
C — Chassis
Steering Handwheel Speed Sensor Signal V High
Views:
UK: 6
EN: 6
RU: 5
AI status
Completed
Completed
100%
Causes
- Damaged sensor (internal short or failed electronics)
- Short to battery voltage on the sensor signal or reference wire
- Poor or missing ground for the sensor or module
- Corroded, loose, or damaged connector or wiring harness
- Faulty control module / ECU input stage
- Electromagnetic interference from nearby damaged components
Symptoms
- Steering or stability control warning light (ABS/ESC) illuminated
- Reduced or altered steering assist / torque assist behavior
- Diagnostic trouble code stored and possible limp/limited functionality
- Erratic or inconsistent steering angle/speed readings in scan data
- Noisy or inconsistent sensor signal on oscilloscope
What to check
- Read freeze-frame and live data with a scan tool; monitor the steering handwheel sensor value and reference voltage
- Visually inspect sensor connector and wiring from sensor to module for damage, corrosion, or pin push-out
- Backprobe the sensor connector with a multimeter to verify reference voltage and signal voltage
- Measure sensor ground continuity to chassis and module grounds
- Unplug sensor: confirm whether the code changes (some ECUs set different codes when sensor open)
- Use an oscilloscope to inspect waveform if available — look for steady DC above expected or superimposed noise
Signal parameters
- Reference supply: typically 5 V nominal (varies by model) — should be stable within manufacturer tolerance
- Normal sensor output: 0–5 V (or frequency output depending on sensor type); waveform should stay within this range
- Fault condition: signal voltage above expected range (often >5.5 V) or near battery voltage (~12 V) indicates short to power
- Expected frequency/variation: sensor output should change smoothly with handwheel rotation (frequency increases with speed)
- Ground continuity: near 0 Ω to chassis ground; high resistance indicates poor ground
Diagnostic algorithm
- Capture freeze-frame and live data for the C0473 event with a capable scan tool. Note reference voltage and exact signal value at fault.
- Visually inspect the steering column area, sensor connector, and wiring harness for physical damage, corrosion, or recent repair signs.
- Backprobe the sensor connector: measure reference voltage, signal voltage, and ground with a digital multimeter. Compare to expected values.
- With ignition on, wiggle wiring and connector while monitoring live data to check for intermittent faults.
- If signal voltage reads near battery voltage, isolate by disconnecting the sensor: if voltage disappears or code type changes, suspect short in harness to B+.
- Use an oscilloscope to verify waveform integrity. Look for a steady DC over-voltage, excessive noise, or missing waveform.
- Check continuity and resistance of the signal and ground circuits from sensor to module; repair any opens, shorts, or high-resistance grounds.
- If wiring and connectors are good, replace the steering handwheel speed sensor and retest.
- If fault remains after sensor replacement, test/backprobe at the module connector for input pin voltage; consult wiring diagram and consider module fault.
- Clear codes and road-test to verify repair. Re-scan to confirm no reappearance. Check for any applicable manufacturer TSBs or calibration updates.
Likely causes
- Short to battery voltage on the sensor signal or 5V reference (most common)
- Failed steering handwheel/speed sensor
- Open/poor ground or corroded connector at sensor
- Wiring harness damage (pinched, chafed, rodent chew)
- Intermittent connector contact or broken wire inside insulation
Fault status
Status
Steering handwheel speed sensor circuit voltage higher than expected. Control module detected a voltage above the allowable threshold on the sensor signal or reference circuit (possible short to battery, sensor failure, or wiring/ground issue).
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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