C1A63

Code

Generic C — Chassis

Electronic Parking Brake Actuator Position Sensor — Intermittent Signal

Brand: Generic

Type: C — Chassis

Views: UK: 11 EN: 18 RU: 12

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Page language: EN

Causes

Loose, corroded or contaminated connector or terminals at the actuator position sensor
Broken, frayed or chafed wiring harness (intermittent open or short)
Water ingress or moisture in connector or actuator body
Faulty EPB actuator position sensor or actuator assembly
Poor or intermittent ground or reference supply to the sensor
Intermittent power supply or blown/loose fuse/relay contact

Symptoms

EPB warning lamp or message on dash
EPB fails to engage or release reliably; intermittent operation
Audible clicking or abnormal noise from EPB actuator during apply/release
Automatic park/auto-hold or hill-hold features disabled or unavailable
Multiple or recurring EPB-related DTCs stored; possible limp/limited brake functionality message
Inconsistent position value in live data (jumps, drops to invalid range)

What to check

Scan vehicle and record stored C1A63 plus any related DTCs and freeze frame data
Check live data for actuator position sensor value while commanding EPB ON/OFF and during manual actuator operation
Visually inspect actuator connector, pins and wiring for corrosion, bent pins, water entry, or damage
Perform wiggle test of harness/backprobe connector while monitoring live data for intermittent changes
Check reference voltage and ground at the sensor connector with a digital multimeter
Measure continuity and resistance of sensor signal, power and ground circuits back to the control module (with ignition off)

Signal parameters

Typical sensor interface: 3-wire (5 V reference, signal, ground) or CAN/serial position message depending on design
Analog-type position: signal usually 0–5 V and should change smoothly as actuator moves (exact voltages manufacturer-specific)
Update rate: position signal or message typically updates multiple times per second (actual rate varies by manufacturer)
Intermittent fault behavior: sudden jumps, dropouts to 0 V or open-circuit, or noisy/unstable waveform when monitored with oscilloscope

Diagnostic algorithm

Connect a capable scan tool and record current and pending codes, freeze frame and live data for the EPB actuator position
Attempt to reproduce the fault: cycle EPB on/off and operate with occupants/ignition state that reproduces issue; watch live position value
Visual inspection: disconnect battery or ignition per service procedure, inspect connector and wiring for contamination, damage, pin backout, corrosion and water ingress; repair or reseal as needed
Backprobe sensor harness with ignition on: verify 5 V reference (if applicable), signal voltage and ground integrity. Note intermittent changes while gently flexing harness and connector (wiggle test)
If intermittent signal appears, use an oscilloscope to capture waveform during actuation to identify noise, dropouts or shorts
Check continuity and resistance of each conductor from sensor connector to the control module; repair any high-resistance or intermittent circuits
Inspect and test related grounds and power feeds; clean and tighten ground connections
If wiring and connectors are good and signals remain intermittent or out of range, replace the EPB actuator or sensor per manufacturer procedure
After repair: clear codes, perform functional test of EPB and complete test drive to confirm fault does not return; re-scan for pending codes

Likely causes

Connector/terminal corrosion or partial contact at the actuator (most common for intermittent faults)
Damaged harness at a flex point or near the wheel/actuator
Moisture contamination inside the actuator or connector
Failed/aging position sensor inside the EPB actuator
Poor ground or intermittent battery/ignition feed to the sensor circuit

Fault status

⚠️ Status

Intermittent signal detected from electronic parking brake actuator position sensor. Fault stored; EPB warning may be displayed and automatic EPB functions may be limited or disabled.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours