Cruise Control Servo Control Circuit High
The P0596 code indicates that the powertrain control module (PCM) has detected a voltage signal from the cruise control servo control circuit that is higher than the specified range. This typically points to a short to voltage, a faulty servo motor, or a wiring issue. The cruise control system uses the servo to adjust throttle position; a high voltage reading can prevent proper operation.
01. Most Common Causes
- Short to voltage in the cruise control servo control circuit
- Faulty cruise control servo motor
- Damaged wiring or connectors in the servo circuit
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Cruise control inoperative
- Check Engine Light illuminated
- Cruise control light flashing or not working
- Possible erratic throttle behavior
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the cruise control servo wiring and connectors for damage, corrosion, or shorts.
Step 3: Test the servo control circuit voltage with a multimeter; compare to manufacturer specifications.
Step 4: Check the servo motor resistance and operation; replace if out of spec.
Step 5: If wiring and servo are okay, test the PCM output; replace PCM if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but cruise control will not work. The vehicle remains drivable, but you should diagnose and repair the issue to restore cruise control functionality.
How much does it cost to fix?▼
Typically between $50 and $150 for parts and labor, depending on the cause. A servo replacement may cost more if the part is expensive.