C0500

Code

Generic C — Chassis

Left Front Wheel Speed Sensor A Circuit/Open

Brand: Generic

Type: C — Chassis

Views: UK: 32 EN: 77 RU: 40

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Page language: EN

Causes

Open or broken sensor wiring (broken conductor, pinched wire, connector disconnected)
Corroded or loose connector or terminals at sensor or control module
Failed wheel speed sensor (Hall-effect or variable-reluctance)
Damaged or missing tone/reluctor ring (chips, cracks, heavy rust, missing teeth)
Damaged wheel bearing or hub affecting sensor gap
Short to power or ground in the sensor circuit

Symptoms

ABS warning lamp illuminated
Traction control / ESC / TCS warning light illuminated or disabled
Possible speedometer or odometer erratic or inoperative (if derived from ABS)
Loss of ABS/traction control functionality for the affected wheel
Diagnostic trouble code stored for LF wheel speed circuit

What to check

Read and record freeze frame / DTCs with a scan tool; note any related codes
Visual inspection of LF sensor, tone ring, harness, and connector for damage or corrosion
Wiggle test wiring and connector while monitoring live wheel speed data to reproduce signal drop
Measure sensor resistance and compare to expected range (see signal parameters)
Check for proper reference voltage/supply and ground at the sensor connector (Hall-type sensors)
Check continuity between sensor connector and ABS module pin for opens

Signal parameters

Passive (variable-reluctance) sensor: DC resistance typically ~200–2000 ohms (manufacturer specific). Produces AC voltage when wheel rotates; low-speed AC often 0.1–1.5 VAC, increasing with speed.
Active (Hall-effect) sensor: reference supply ~4.5–5.5 VDC at sensor; output is a switching square wave 0–5 V (or open-collector pulled to system voltage), frequency proportional to wheel speed.
Expected waveform: clean alternating pulses (VR) or clean square pulses (Hall) without dropouts. No continuity (open) indicates sensor failure or broken conductor.
Typical connector pin voltages: one pin supply (~5 V), one pin ground (0 V), one pin signal (pulsing).

Diagnostic algorithm

Verify code: Connect scan tool, confirm C0500 is active or stored, and review live data for LF wheel speed channel.
Visual inspection: With vehicle safely supported, inspect LF sensor harness and connector at hub, strut, and along routing to chassis for damage or corrosion.
Connector check: Disconnect sensor connector, inspect terminals for corrosion, bent pins, or water ingress; clean and reseat.
Resistance/continuity: With ignition off, measure resistance of sensor leads (for passive type); an open/OL indicates sensor failure. Check continuity from sensor pins to ABS module pins to locate open circuits.
Supply/ground check: With key on, backprobe connector to verify reference voltage (≈4.5–5.5 V) and ground presence for active/Hall sensors.
Dynamic output test: Spin the wheel (safely with vehicle raised) while monitoring AC voltage (VR) or signal waveform (Hall) with multimeter/oscilloscope. Look for clean pulses without dropouts.
Wiggle test: Have helper gently move harness and connector while monitoring live data/waveform to detect intermittent opens.
Inspect tone ring/bearing: Check tone ring for missing/damaged teeth, heavy rust, or excessive air gap; check wheel bearing play that may change sensor gap.
Repair: Repair wiring or connector faults, replace sensor or tone ring as indicated. After repair, clear codes and road test to verify no recurrence.
Module check: If wiring and sensor verify OK, consult manufacturer module wiring diagrams and consider ABS module input circuit testing or replacement.