What it means
Same as P0594 with the control line shorted to supply. 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 that moves the throttle actuator. P0596 sets when the module detects the control line above its expected electrical range, often because it is shorted to supply voltage; cruise control may be unavailable or disengage.
Common causes
Most likely first.
- Control line shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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 P0596 and review freeze-frame data and servo command status to determine when the control line went high.
- Inspect the servo control harness and connectors for a pinched wire touching B+, chafing, moisture, corrosion, or pushed-back pins.
- Using the wiring diagram, test the control line for a short to supply voltage and check connector terminal contact.
- Wiggle the harness while monitoring the circuit or scan-tool data to locate an intermittent short.
- If the external wiring is sound, test the servo and control module according to the manufacturer's specification.
Common fixes
- Repair or reroute a pinched servo control wire that contacts a supply wire.
- Repair chafed insulation and secure the harness away from supply wiring.
- Clean or replace corroded or damaged connector terminals.
- Replace a failed servo or module only after the wiring tests correctly.
Can I keep driving?
Driving is generally possible if normal throttle and braking operation are unaffected, but avoid cruise control until the fault is fixed. Stop using it if it fails to hold speed or disengages unexpectedly.
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.