P0578Generic code

P0578 Code: Cruise Control Multi-Function Input A Circuit Stuck

The P0578 code means the computer sees a fault in the signal from the cruise control switches, with multi-function input A stuck. Cruise control is disabled, and the rest of the vehicle works normally. A worn clockspring or a sticking button is the usual cause.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$20 to $400
Difficulty
Medium
System
Idle and Speed Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0578 code means

The cruise control switches, on the steering wheel or on a stalk, send their orders to the computer over one or more wires. Many manufacturers use one line with a different resistance for each button, and the computer recognizes the pressed button by the voltage it measures.

The P0578 code means the computer sees a signal that matches no button, a signal that stays fixed as if a button were held down all the time (the stuck condition), or a signal that does not agree with the second control line. For safety, it disables cruise control.

The most common cause is the steering wheel clockspring, which connects the buttons to the vehicle through a ribbon that wears as the wheel turns. Buttons that are dirty or soaked with spilled liquid are another usual cause.

Always start with the simple checks: fuse, relay and connector. Then check power, ground and signal with the component connected (using back-probe pins), and finally the continuity of each wire to the computer. Replace the component only if all of that is good.

P0578 code symptoms

  • Cruise control that does not work.
  • Check engine light or cruise control light on.
  • Sometimes the horn or the steering wheel buttons also fail (clockspring).

Likely causes of the P0578 code

  1. Damaged steering wheel clockspring. The internal ribbon breaks with use.
  2. Steering wheel buttons that are dirty or damaged by spilled liquids.
  3. Control module connector with a loose, intermittent contact.
  4. Brake switch, if it affects the cancel signal.

How to diagnose the P0578 code step by step

  1. Read the status of each button on the scan tool while you press it. Only the pressed button should change.
  2. Measure the resistance of the controls in each position and compare it with the manufacturer table.
  3. Inspect the clockspring if the horn, the airbag light or the steering wheel buttons also fail.
  4. Check the brake switch.

How to fix the P0578 code

  • Replace the clockspring or the steering wheel controls.
  • Clean the button contacts.
  • Repair the wiring.
  • Clear the code and test cruise control.

Technical reference data

  • Resistor ladder controls: each button gives a different voltage on the same line.
  • Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

Before you work on the steering wheel, disconnect the battery and wait a few minutes. The driver airbag can deploy.

P0578 on Ford

On many Ford vehicles the clockspring is a frequent failure.

P0578 on GM

On many GM vehicles the clockspring is a frequent failure.

P0578 on Chrysler

On many Chrysler vehicles the clockspring is a frequent failure.

Frequently asked questions about P0578

Can I drive with the P0578 code?
Yes. It only affects cruise control. The engine, brakes and the rest of the vehicle work normally, and there is no safety risk while driving.
What is the clockspring?
It is a coiled ribbon in the steering column that connects the airbag and the buttons to the vehicle even as the steering wheel turns. When it wears out, the buttons stop working.
Is it dangerous to remove the steering wheel?
Yes, because of the airbag. Follow the manufacturer procedure, disconnect the battery and wait before touching anything.
How much does it cost to fix P0578?
Between $20 and $400. A cleaned contact or a repaired wire is cheap, and a clockspring or steering wheel controls cost more.
What does the P0578 code mean?
The P0578 code is a generic OBD2 code for a stuck signal in cruise control multi-function input A. The computer does not accept the switch signal, so it shuts the system down.
What is the most common cause of P0578?
A worn clockspring in the steering wheel, followed by dirty or sticking buttons and a loose connector.

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