P0573 OBD II Trouble Code Cruise Control/Brake Switch A Circuit High

How to quickly diagnose, repair, and causes of a P0573 diagnostic code that indicates a detected high voltage condition in the cruise control brake switch A circuit.

Symptoms of P0573 OBD II Trouble Code

  • Cruise control completely inoperative
  • Erratic cruise control operation
  • Certain functions not operating as they should (e.g. set,resume, accel., etc.)
  • Cruise control turning on but not engaging
  • No brake lights if the brake light switch is faulty

Common Causes of P0573 OBD II Trouble Code

  • Cruise control/Brake switch defective
  • Wiring issue (e.g. pinched on brake pedal, chafed, etc.)
  • ECM (engine control module) issue (i.e. internal short, open, etc.)
  • Debris/dirt mechanically hindering brake switch operation
  • Brake switch not adjusted properly
  • Brake switch out of it's mount

Severity of P0573 OBD II Trouble Code

Usually, with cruise control systems, I would say severity is set to low. But in this case, I will go with moderately-severe. The fact that there is a possibility of this fault causing the brake switch to malfunction, or vice-versa, is a significant concern.