Cruise Control Input Circuit High
The P0577 code indicates that the powertrain control module (PCM) has detected a high voltage signal from the cruise control input circuit. This typically occurs when the brake switch or cruise control switch is stuck in the closed position, or there is a short to voltage in the wiring. The PCM monitors the voltage on the cruise control input circuit; when it exceeds the normal range (usually above 4.5V), it sets this code. This can prevent the cruise control from engaging or cause it to disengage unexpectedly.
1. Most Common Causes
- Faulty brake switch (stuck closed)
- Short to voltage in cruise control wiring
- Faulty cruise control switch
- Corroded or damaged connector
- Failed PCM (rare)
2. Symptoms You Will Notice
- Cruise control inoperative
- Cruise control disengages unexpectedly
- Brake lights may stay on or not work
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0577 and check for other codes.
Step 2: Inspect the brake switch for proper operation; test with multimeter.
Step 3: Check cruise control wiring and connectors for shorts, opens, or corrosion.
Step 4: Test the cruise control switch resistance per manufacturer specs.
Step 5: If all else is fine, consider PCM failure and reprogram or replace.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive, but the cruise control will not work. If the brake switch is faulty, brake lights may malfunction, which is a safety concern. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause. A brake switch replacement is usually under $100, while wiring repairs may be more.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.