Code
C100A
LAND ROVER
C — Chassis
Brake pedal position sensor
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UK: 6
EN: 9
RU: 5
AI status
Completed
Completed
100%
Causes
- Faulty brake pedal position sensor (internal failure or wear)
- Damaged, chafed or disconnected wiring harness to the sensor
- Corroded or loose connector pins at the sensor or control module
- Poor sensor ground or missing reference voltage
- Short to battery or ground in the signal circuit
- Mechanical binding, damaged pedal linkage, or misadjusted sensor mounting
Symptoms
- Brake warning, ABS, or traction/stability control warning lamp illuminated
- Cruise control inoperative or disabled message
- Possible reduced engine or torque management response when braking (in some models)
- Irregular brake light behavior or brake lights stuck on/off
- Diagnostic trouble code stored (C100A) and possibly related codes
- Intermittent faults that occur when moving or flexing the pedal/wiring
What to check
- Connect a diagnostic scan tool; record C100A and any related codes, freeze frame, and live data
- Visually inspect sensor, pedal linkage, connector, and wiring harness for damage or corrosion
- Wiggle harness and connector while monitoring live BPP signal to reproduce fault
- Backprobe the sensor connector to check reference voltage (usually 5 V or ignition reference), signal voltage, and ground
- Measure continuity and resistance of signal and ground wires to the control module (ignition OFF)
- Compare signal voltage at rest and during full pedal travel; check for smooth, proportional change
Signal parameters
- Common reference: 5 V (or ignition reference) supply to sensor; confirm with vehicle data
- Typical signal voltage range: ~0.5–4.5 V across pedal travel for potentiometer/Hall sensors (varies by model)
- At rest (no brake): low-end voltage (typically ~0.5–1.5 V); when fully pressed: high-end (~3.5–4.5 V)
- Some systems use dual redundant sensor circuits (BPP1 / BPP2) that must correlate within specification
- Open circuit: signal near 0 V or battery voltage (short to B+); short to ground: ~0 V
- Digital/CAN systems: BPP data may appear as a CAN message — check communication integrity if analog signal not present
Diagnostic algorithm
- Read and record all DTCs and freeze frame data with a capable scan tool. Note whether multiple brake or communications codes are present.
- Perform a visual inspection of the pedal area, sensor mounting, wiring and connector for damage, contamination or loose pins.
- With ignition ON (engine off), backprobe the sensor connector: verify reference voltage (typically ~5 V), good ground, and measure the signal voltage at rest.
- Slowly depress and release the pedal while watching the live signal value: signal should change smoothly without jumps, dropouts or dead zones. If dual sensors exist, ensure both channels correlate.
- If signal is absent or out of range, check continuity of the signal and ground wires to the control module with ignition OFF. Repair any opens/shorts or poor grounds.
- Wiggle the harness and connector while monitoring live data to locate intermittent faults. Repair/replace damaged wiring or connectors as required.
- If wiring and supply/ground are good but signal is still faulty, substitute a known-good sensor (if available) or replace the BPP sensor.
- After replacement or repair, clear codes, perform any required sensor or pedal calibration/learn procedure per manufacturer instructions, then road test to confirm the fault is resolved.
- If fault persists with a verified good sensor and wiring, investigate the receiving control module (ABS/BCM/PCM) for internal fault or communication issues and consult technical service information.
Likely causes
- Open or shorted signal wire between BPP sensor and control module
- Bad ground or poor reference voltage at the sensor connector
- Internal sensor potentiometer or hall element failure
- Bent/dirty connector pins causing intermittent signal
- Pedal return spring weak or pedal geometry preventing full travel detection
- Recent work in the area (airbag, steering, dash) disturbed wiring or connectors
Fault status
Status
C100A indicates the brake pedal position sensor circuit is reporting an invalid or out-of-range signal to a vehicle control module. This can be caused by a bad sensor, wiring/connector faults, poor reference/ground, or module communication issues. The condition may disable cruise control and affect brake/ABS/traction-control functions until corrected. Further diagnostic checks are required to identify the root cause.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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