C1337

Code

Generic C — Chassis

ABS wheel speed sensor circuit failure

Brand: Generic

Type: C — Chassis

Views: UK: 8 EN: 8 RU: 11

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Page language: EN

Causes

Open or shorted sensor wiring (chafing, pinched, broken)
Corroded or loose connector or terminals
Failed wheel speed sensor (passive or active)
Damaged or contaminated tone/reluctor ring (missing teeth, debris)
Poor ground or reference voltage to active sensor
Intermittent connector contact from moisture or movement

Symptoms

ABS warning lamp and/or traction control light illuminated
ABS/ESC not functioning or disabled
Intermittent ABS activation or unexpected ABS behavior under braking
Speedometer or cruise control erratic (on some vehicles)
Uneven braking feel or longer stopping distances in slippery conditions
Diagnostic trouble codes related to wheel speed sensors or communication

What to check

Read freeze-frame data and live wheel speed values with a scan tool; look for one wheel speed not matching others
Visually inspect sensor, wire harness, connectors, and reluctor ring for damage or debris
Wiggle/operate wiring and connectors while monitoring live data for intermittent changes
Check connector pins for corrosion, bent pins or pushed-out terminals
Measure sensor resistance and compare to manufacturer spec (for passive sensors)
Measure sensor signal while spinning the wheel (AC volts for passive, square wave 0–5V for active)

Signal parameters

Passive (variable reluctor) sensors: generate AC voltage proportional to speed; low-speed output often ~0.1–1.0 VAC and increasing with speed (can reach several VAC at higher rpm)
Active (Hall or magnetoresistive) sensors: square/pulse output typically 0–5 V or 0–12 V depending on vehicle; reference supply commonly ~5 V
Typical DC resistance (passive sensors): varies widely by manufacturer — commonly from a few hundred ohms to a few kilo-ohms; check vehicle spec
Pulse frequency: proportional to wheel speed and tooth count; expect steady, regular pulses without dropouts
Signal characteristics to watch for: missing pulses, noisy waveform, low amplitude, or intermittent signal

Diagnostic algorithm

Retrieve all ABS/vehicle codes and freeze-frame data. Note which wheel is identified and any related codes.
With ignition on, observe live wheel speed readings while slowly rotating each wheel. Identify any wheel that fails to report or shows dropouts.
Perform a visual inspection of the suspect wheel sensor, wiring harness routing, and reluctor ring. Repair any obvious damage or debris.
Disconnect sensor connector and inspect pins for corrosion, damage, or moisture. Clean contacts and reseat connector; apply dielectric grease afterwards if appropriate.
For passive sensors: measure DC resistance of the sensor and compare to spec. Check for open/short. For active sensors: check reference voltage and ground at connector.
Spin the wheel and measure sensor output with a multimeter (AC volts) or oscilloscope (preferred). Confirm clean, regular waveform and proper amplitude.
Wiggle the harness, move suspension components and connectors while watching live data or waveform for intermittent faults.
Check continuity and insulation between sensor connector and ABS module connector; verify no shorts to ground or battery.
Inspect reluctor ring runout, missing teeth or heavy corrosion; measure air gap between sensor and tone ring to spec.
If tests point to a failed sensor, replace the sensor and retest. If wiring or connector fault found, repair or replace harness and retest.
If sensor and wiring test good and signals reach ABS module correctly, consider ABS module input or internal fault and consult manufacturer procedures for module testing or replacement.
Clear codes and perform a test drive to confirm the fault does not return.

Likely causes

Sensor wiring rubbed through at suspension/steering pivot points
Connector contaminated with water/road salt causing intermittent readings
Reluctor ring has missing or damaged teeth or heavy rust
Connector pins pushed out or bent at sensor/ECU
Sensor failed due to impact or internal short

Fault status

⚠️ Status

ABS control module reports wheel speed sensor circuit malfunction — possible open/short/intermittent signal or sensor failure. ABS/traction control may be disabled.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3 hours