P0585 Cruise Control Multi-Function Input A/B Correlation

P0585 points to Cruise Control Multi-Function Input A/B correlation. The controller sees disagreement between two cruise switch input paths that should match a valid command pattern.

Code details

Generic OBD-II · P0

System: Speed / Idle
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace one switch bank until the A and B input correlation pattern is measured.

Symptoms of P0585

Unstable, high, or low idle, or stalling.
Erratic speedometer, cruise-control, or shift behaviour.
Check-engine light with a hesitation or surge.

Common causes of P0585

A dirty throttle body, idle-control valve, or throttle-position sensor.
A failing vehicle-speed or wheel-speed sensor, or its wiring.
Vacuum leaks or a related sensor forcing the idle/speed strategy.

Useful checks before replacing parts

Compare input A and B switch data, individual cruise commands, brake and clutch inputs, vehicle speed, and freeze-frame conditions.
Inspect resistor ladder circuits, steering wheel switches, clockspring wiring, shared references, connector corrosion, and liquid intrusion.
Operate each cruise function while verifying that both input channels change in the expected relationship.

Related OBD-II codes

These nearby speed / idle entries can help compare wording and pin down the fault area.