Cruise Control/Brake Switch A Circuit High
The P0573 code indicates that the Powertrain Control Module (PCM) has detected a high voltage signal from the brake switch A circuit. This typically means the brake switch is stuck closed (always on) or there is a short to voltage in the wiring. The brake switch is a critical safety component that disengages cruise control when the brake pedal is pressed. A high circuit condition can prevent cruise control from engaging or cause it to disengage unexpectedly.
01. Most Common Causes
- Faulty brake switch (stuck closed)
- Short to voltage in brake switch circuit
- Corroded or damaged brake switch connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Cruise control inoperative
- Brake lights may stay on constantly
- Cruise control disengages unexpectedly
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check freeze frame data.
Step 2: Inspect the brake switch and its connector for damage, corrosion, or misalignment.
Step 3: Test the brake switch operation: with pedal released, switch should be open (no continuity); with pedal pressed, switch should be closed (continuity).
Step 4: Check for voltage at the brake switch signal wire. With pedal released, voltage should be near 0V; with pedal pressed, voltage should be battery voltage. If voltage is present when pedal is released, there is a short to voltage.
Step 5: Repair or replace the brake switch or wiring as needed, then clear the code and test drive.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive, but cruise control will not work. If brake lights stay on, it can drain the battery and confuse other drivers. Have it repaired soon.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, depending on whether the switch or wiring needs replacement.