What are the common causes of C05C3?

An open or high resistance in the brake booster motor A supply. A blown fuse or open relay feeding motor A. A loose or corroded motor A power connector. A failed phase driver cutting power to motor A. A damaged motor A supply wire.

Check the fuse and relay feeding brake booster motor A. Check the motor A power connector for corrosion or looseness. Test the motor A supply wire for an open. Check the supply voltage at motor A under load. Replace the brake booster motor if supply is present but it does not run. Clear the code and retest.

C05C3

Brake Booster Motor A Supply Circuit

System: Chassis control (C code)
Lamp: Chassis Warning Light
Category: Chassis

What it means

C05C3 means Brake Booster Motor A Supply Circuit.

Check these first

An open or high resistance in the brake booster motor A supply
A blown fuse or open relay feeding motor A
A loose or corroded motor A power connector
A failed phase driver cutting power to motor A
A damaged motor A supply wire

What to do next

Check the fuse and relay feeding brake booster motor A
Check the motor A power connector for corrosion or looseness
Test the motor A supply wire for an open
Check the supply voltage at motor A under load
Replace the brake booster motor if supply is present but it does not run
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.