Cruise Control Servo Control Circuit High
The P0596 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the cruise control servo control circuit. This circuit controls the servo motor that adjusts the throttle position to maintain set speed. A high voltage reading suggests a short to power, a faulty servo, or a wiring issue. This can disable the cruise control system and may affect throttle response.
1. Most Common Causes
- Short to power in the cruise control servo circuit
- Faulty cruise control servo motor
- Damaged wiring or connector in the servo circuit
- Failed PCM (rare)
2. Symptoms You Will Notice
- Cruise control inoperative
- Check Engine Light illuminated
- Possible erratic throttle behavior
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0596 and check for other codes.
Step 2: Visually inspect the cruise control servo wiring and connector for damage or corrosion.
Step 3: Test the servo circuit voltage with a multimeter; compare to manufacturer specs.
Step 4: Check the servo motor resistance; replace if out of range.
Step 5: If wiring and servo are good, test the PCM output; replace PCM if faulty.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but cruise control will be disabled. The vehicle remains drivable, but have it diagnosed soon to avoid potential throttle issues.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair, but could be higher if the servo or PCM needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.