C05BC

Code

Generic C — Chassis

Brake Booster Motor B Position Sensor Supply Circuit/Open

Brand: Generic

Type: C — Chassis

Views: UK: 19 EN: 50 RU: 31

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Open or short in the sensor supply (reference) wire
Poor or corroded connector/terminal at the sensor or harness
Failed Brake Booster Motor B position sensor (internal open)
Blown fuse or fault in the module power/ground feeding the sensor supply
Intermittent wiring damage (chafing, broken conductor) or pin pushed out of connector

Obtain freeze frame/live data with a scan tool; verify code and related codes
Visually inspect the sensor connector and wiring for damage, corrosion, or disconnection
Check fuses and power supplies that feed the brake booster control circuits
Backprobe the connector and measure reference supply voltage with ignition ON
Wiggle test harness while monitoring live data or supply voltage for intermittent faults

Reference supply voltage typically 5.0 V (or 3.3 V) — consult vehicle-specific data
Expected sensor signal (position) varies with actuator travel; typically 0.5–4.5 V
Open/supply missing: measured ~0.0 V at sensor supply pin with ignition ON
Short to battery: measured near battery voltage (~12 V) at the supply pin
Continuity: low ohms between sensor supply pin and ECU reference output when ignition OFF

Verify DTC and note freeze-frame/live-data values with a scan tool; check for related codes (e.g., other booster sensor faults, communication faults).
Visually inspect sensor connector and wiring harness for damage, corrosion, melted insulation, or pin damage. Repair obvious issues.
With ignition ON (engine off), backprobe the sensor connector: measure reference supply voltage at the supply pin. Compare to vehicle spec (commonly 5 V or 3.3 V).
If supply voltage is present at the ECU connector but absent at the sensor connector, perform continuity/resistance check on supply wire between ECU and sensor. Repair any open circuit.
If supply is absent at the ECU reference output, inspect fuses/relays and check ECU/module ground and power circuits. Test for short to ground on the supply circuit.
If supply is present and wiring checks good, measure sensor signal and ground; verify sensor output varies with booster/motor movement. Replace sensor if internal open or out of spec.
After repairs, clear codes, perform functional test and road test to confirm fault does not return. If intermittent, perform extended driving or environmental tests (wiggle/heat/cold) while monitoring live data.
If diagnostics are inconclusive, consult manufacturer wiring diagrams and use an oscilloscope or specialized test procedures to further isolate intermittent or complex faults.