Brake Switch "A"/"B" Correlation
Modern vehicles use two redundant brake switch signals (often one normally-open and one normally-closed). When the two signals disagree, this code is set; common causes include a misadjusted switch, internal switch failure, or wiring fault.
Affected components
- Brake light switch
- Brake switch wiring
Common causes
- High likelihood: Brake switch misadjusted
- Medium likelihood: Brake switch internal fault
Diagnostic notes
- The malfunction indicator lamp may illuminate
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.