Cruise Control Multi-Function Input Circuit Stuck
The P0590 code indicates that the powertrain control module (PCM) has detected a stuck signal from the cruise control multi-function input circuit. This circuit typically includes inputs from the steering wheel controls (set, resume, cancel, etc.) and the brake switch. When the signal remains in a fixed state (e.g., always high or low) for an extended period, the PCM sets this code. Common causes include a faulty cruise control switch, a shorted or open wiring, a defective brake switch, or a PCM issue. This can prevent the cruise control from engaging or cause erratic operation.
1. Most Common Causes
- Faulty or worn cruise control multifunction switch
- Short to ground or voltage in the 'B' circuit wiring
- Open circuit or excessive resistance in the 'B' circuit wiring
- Corroded or bent pins in the cruise control switch connector
- Internal failure of the engine or powertrain control module (ECM/PCM)
- Dirt or moisture buildup in the steering wheel switch or column
2. Symptoms You Will Notice
- Cruise control inoperative
- Cruise control cannot be set or resumed
- Cruise control disengages unexpectedly
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check for additional codes.
Step 2: Inspect the cruise control switch and wiring for damage, corrosion, or loose connections.
Step 3: Test the brake switch operation and adjust or replace if faulty.
Step 4: Check the cruise control circuit voltage and continuity with a multimeter.
Step 5: If all else fails, replace the cruise control multi-function switch and clear the code.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the cruise control will not function. The vehicle's braking and other systems remain unaffected.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, including parts and labor. A new cruise control switch costs around $20-$60, and labor is about $30-$90.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.