What it means
Same as P0594 with the control line shorted to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The cruise-control servo control circuit carries the command used to move the throttle actuator. P0595 sets when the module detects the control line below its expected electrical range, commonly because the line is shorted to ground; cruise control may fail or disengage.
Common causes
Most likely first.
- Control line shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Cruise control unavailable or disengages
- Cruise-control speed may not hold
- Check-engine light
How to diagnose it
- Use a scan tool to confirm P0595 and review freeze-frame data and servo command status to see when the control line went low.
- Inspect the servo wiring and connectors for insulation rubbed through to ground, moisture, corrosion, loose pins, or pin push-back.
- Using the wiring diagram, test the control line for a short to ground and check connector contact quality.
- Wiggle the servo harness while monitoring the circuit or scan-tool data to identify a fault that appears only with movement.
- If the wiring is sound, test the servo and control module against the manufacturer's specification.
Common fixes
- Repair chafed servo control wiring and protect it from rubbing against grounded metal.
- Clean or replace corroded connector terminals and secure loose or pushed-back pins.
- Repair a control line shorted to ground.
- Replace a failed servo or module only after the external circuit tests correctly.
Can I keep driving?
You can generally drive if the throttle and brakes operate normally, but do not use cruise control while it is unreliable. A speed-holding problem may cause unexpected disengagement.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.