Cruise Control Multi-Function Input A / B Correlation
Your cruise control system is detecting mismatched signals between two input switches or sensors that should agree with each other. Think of it like two people trying to open a door together—if their hand positions don't match up, the door won't open smoothly.
The ECU monitors dual cruise control input signals (typically from steering wheel buttons or stalks) and expects them to correlate logically. When one signal activates, the other should follow within defined timing and voltage windows. A mismatch suggests a wiring fault, switch failure, or sensor inconsistency.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Cruise Control Switch A vs B Signal Correlation | Signals match within 50-100ms and voltage ranges align | Signals diverge beyond acceptable tolerance or timing mismatch detected |
| Multi-Function Input Voltage | 0.5-4.5V (vehicle-dependent), consistent behavior | Erratic voltage spikes, dropouts, or cross-talk between channels |
Code P0585 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0585 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.