HomeTrouble CodesP0585

P0585 — Cruise Control Multi Function Input Ab Correlation

Generic OBD-II · all makesPowertrain (engine & transmission)

This code indicates that the engine computer has detected a mismatch between two or more cruise control input signals. In other words, the signals from the cruise control switches or related pedal switches do not agree with each other as the computer expects. The system typically disables cruise control until the fault is resolved.

Symptoms

What causes it — most likely first

1. Faulty cruise control multi-function switch

The steering wheel or stalk switch assembly that provides cruise inputs can wear internally, causing one or more signals to disagree with the others. This is the most common source of a correlation fault.

2. Wiring or connector fault in cruise control circuit

Corroded, chafed, or loose wiring between the cruise switch and the PCM can alter or drop one signal while others remain normal, triggering the correlation code.

3. Failed clock spring

The rotating electrical contact behind the steering wheel can develop an open or high-resistance circuit on one cruise input line, especially on higher-mileage vehicles.

4. Misadjusted or faulty brake/clutch pedal position switch

The PCM compares cruise switch inputs with brake and clutch disengagement signals. A pedal switch that reports the wrong state can create a correlation conflict.

5. PCM software or internal fault

A rare cause. The computer may misinterpret valid inputs due to a software calibration issue or, very uncommonly, an internal input circuit failure. This should only be considered after all switch and wiring inputs are verified.

How it's diagnosed

  1. Read all stored codes and freeze-frame data; note whether any brake, clutch, or throttle position codes are also present that could affect correlation logic.
  2. Use a scan tool with live data to observe each cruise control switch input state while operating the cruise buttons; identify which signal does not change or disagrees.
  3. Inspect the cruise switch connector, clock spring, and related harness for corrosion, bent pins, or chafed wiring, especially where the harness rotates with the steering wheel.
  4. Back-probe or use a multimeter to confirm continuity and voltage on each cruise input line between the switch and PCM.
  5. Verify brake and clutch pedal position switch operation and adjustment, since these inputs are part of the correlation check.
  6. Only after all switch, wiring, and pedal inputs are proven correct should PCM software calibration or replacement be evaluated.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make

Frequently asked

Is it safe to drive with code P0585?

Yes, it generally does not affect engine operation or braking. The main inconvenience is that cruise control will likely be disabled until the fault is fixed.

Will replacing the PCM fix P0585?

Almost never. The correlation fault is normally caused by a switch, wiring, clock spring, or pedal position input disagreeing with the others. PCM replacement should be a last resort only after every input has been verified correct.

Can a bad clock spring cause this code?

Yes. The clock spring carries cruise switch signals from the steering wheel to the rest of the vehicle, and a worn or damaged clock spring can drop one signal while others work, producing a correlation error.

Can I still use cruise control with this code?

Usually not. Most vehicles disable cruise control when this code is active as a safety measure, even if the buttons appear to respond intermittently.