TorqueMech OBD Code Guide
P0504 - Brake Switch A/B Correlation
The ECM detected a mismatch between brake switch A and B signals.
Code first. Confirm symptoms and checks before pricing parts.
Read code pattern
Check likely system
Estimate after confirmation
Common Next Steps
Turn the code into the next check.
Measure pads and rotors
Confirm thickness, scoring, heat spots, and inner/outer wear.
Inspect caliper movement
Check slide pins, piston movement, hose restriction, and drag.
Check hub runout/play
Use when vibration or ABS evidence overlaps brake complaints.
Related Inspection
Code Overview
The ECM detected a mismatch between brake switch A and B signals.
Common Causes
- Failed sensor or idle control component
- Damaged wiring or connector
- Throttle body or switch issue
Diagnostic Steps
- Inspect the related connector and harness
- Compare live data to vehicle behavior
- Check for mechanical sticking or adjustment problems
Related OBD Codes
Browse nearby codes when systems overlap.
Next Steps
Move from code to checks, then estimate.