The C101C OBD2 fault code relates to the Brake Vacuum Pump circuit. This is part of the vehicle's chassis control system. When a circuit failure occurs, the control module cannot properly monitor or regulate this system, which may affect braking, traction, stability, or suspension performance.
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Symptoms
- Brake warning light on
- ABS light on
- Brake pedal feels different
- Possible brake fluid leak
- Regenerative braking may not work
Common Causes
- Faulty component — internal damage or wear affecting the Brake Vacuum Pump
- Wiring issues — broken, corroded, or chafed wires in the circuit
- Connector problems — loose, oxidized, or moisture-damaged pins
- a general circuit failure is detected — can result from wiring faults, connector issues, or component failure
- Control module fault — rare, but the chassis control module may have an internal fault
Step-by-Step Diagnosis
- Scan with OBD2 tool — Confirm C101C is active. Check for additional chassis DTCs.
- Visual inspection — Examine the Brake Vacuum Pump wiring and connector for corrosion or damage.
- Check voltage and ground — Use a multimeter to verify proper reference voltage.
- Test component — Compare readings to factory specs. A stuck or erratic signal confirms failure.
- Check for shorts/opens — Perform continuity tests on the wiring between the component and control module.
Repair & Solutions
- If the component is defective, replace the Brake Vacuum Pump with an OEM or quality aftermarket part.
- Repair any damaged wiring or connectors using proper methods.
- Clear the DTC with an OBD2 scanner and test drive to verify the code does not return.
- If the code persists after component replacement, inspect the control module connector or consider module testing.
Related Codes
- Related codes depend on specific vehicle configuration
External References & Code-Specific Resources
- Technical reference for C101C
- Diagnostic guide for C101C
- OBD2 code database