Cruise Control Multi-Function Input Circuit High
The P0593 code indicates that the powertrain control module (PCM) has detected a high voltage signal from the cruise control multi-function input circuit. This circuit typically carries signals from the steering wheel controls (set, resume, cancel, etc.) to the PCM. A high voltage condition can be caused by a short to power, a faulty switch, or a wiring issue. This prevents the cruise control system from operating correctly.
01. Most Common Causes
- Short to battery voltage in the cruise control switch circuit
- Faulty cruise control multi-function switch
- Damaged wiring or connector in the cruise control circuit
- Corroded or loose electrical connections
02. Symptoms You Will Notice
- Cruise control inoperative
- Cruise control light on dash may flash or stay on
- Engine Check Light illuminated
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and note freeze frame data.
Step 2: Visually inspect the cruise control switch and wiring for damage or corrosion.
Step 3: Using a multimeter, check the voltage at the cruise control switch connector. Compare with manufacturer specifications.
Step 4: Test the cruise control switch continuity per service manual.
Step 5: If wiring and switch are okay, check for a short to power in the circuit between the switch and PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but cruise control will not work. The vehicle can be driven normally without cruise control.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on the cause. Replacing a cruise control switch can cost $30-$100, plus labor.