Code
C1551
MITSUBISHI
C — Chassis
Hall-IC output voltage
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UK: 13
EN: 19
RU: 13
AI status
Completed
Completed
100%
Causes
- Damaged or faulty Hall‑IC sensor
- Open, shorted or corroded connector/wiring (power, ground or signal)
- Incorrect air gap or mounting position (sensor vs tone wheel/reluctor)
- Contaminated sensor (metal filings, rust, grease) or damaged reluctor/magnet
- Intermittent connection from moisture/loose pin
- Faulty ABS/traction control/engine control module (rare)
Symptoms
- ABS and/or traction control warning light illuminated
- Loss of ABS/TCS functionality or reduced braking performance during hard stops
- Intermittent or incorrect speedometer/odometer or cruise control behavior (if sensor used for vehicle speed)
- Diagnostic trouble code stored and possibly freeze frame data
- Possible juddering or unusual feel at low speeds if wheel speed sensor affected
What to check
- Read stored codes and freeze‑frame data with a scan tool; note which sensor/axle is referenced
- Visually inspect sensor, connector and wiring for damage, corrosion, water entry or loose pins
- Check fuses and power supply circuits for the sensor/ABS module
- Measure reference voltage and ground at the sensor connector with key on
- Backprobe sensor signal while rotating wheel/shaft; observe for pulsed output or steady fault
- Perform wiggle test on wiring while monitoring live signal for intermittent drops
Signal parameters
- Typical supply/reference voltage: commonly 5 V (some older systems 12 V). Consult service manual for exact value.
- Output signal: digital square wave or open‑collector pulsed signal ranging from 0 V to Vref (0–5 V or 0–12 V depending on system)
- At rest: output may be steady high or low depending on sensor design; when rotating, frequency increases proportionally to speed
- Typical sensor resistance (if applicable): varies widely by design — check factory spec. Do not rely on resistance alone for Hall‑IC diagnosis.
- Expected signal: clean pulse train without noise, dropouts or stuck high/low states
Diagnostic algorithm
- Connect a scan tool, confirm C1551 presence and note any related codes or freeze frame data to identify which sensor or circuit is involved.
- Perform a visual inspection of the indicated sensor, its connector and wiring harness for physical damage, corrosion, or contamination.
- With ignition ON (engine off unless specified), backprobe the sensor connector and verify reference voltage and ground are within factory tolerances.
- Rotate the wheel/shaft by hand (or road test safely) while monitoring the signal line with a multimeter or oscilloscope. Look for a consistent pulsed waveform; note amplitude and any dropouts.
- If signal is absent or out of range, wiggle the wiring and connector to try to reproduce the fault; repair any chafed wiring or bad pins found.
- Check air gap and mounting position relative to the tone wheel/reluctor; correct to specification if out of tolerance.
- If wiring and mounting are good but signal remains faulty, replace the sensor with a known‑good unit and re‑test.
- Clear codes and perform a road test to verify the fault does not return. If code persists after sensor and harness remediation, consider module input circuit testing or module replacement per service manual.
Likely causes
- Wiring harness chafe or rubbed through causing signal short to ground or power
- Corroded connector pins at sensor
- Sensor failure from impact or water ingress
- Reluctor wheel or magnetic target damaged or missing
- Poor sensor mounting or excessive air gap
Fault status
Status
Hall‑IC sensor output voltage abnormal — signal missing, stuck or out of expected range; check sensor, wiring, and reference voltage.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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