P0589 Cruise Control Multi-Function Input B Circuit

P0589 indicates a Cruise Control Multi-Function Input B circuit issue. The controller sees an invalid signal from the second cruise switch input group.

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 cruise output components before verifying the input B switch circuit.

Symptoms of P0589

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 P0589

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 B data, input A data, individual cruise switch states, brake status, vehicle speed, and freeze-frame conditions.
Inspect steering wheel switch contacts, clockspring wiring, resistor ladder circuits, connector corrosion, shared reference circuits, and module communication.
Operate each input B function while monitoring live data to identify missing, stuck, or implausible values.

Related OBD-II codes

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