P0566: Cruise Control Off Signal Malfunction

Is your scanner showing P0566?
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P0566: Cruise Control Off Signal Malfunction

DIY Difficulty Level
Repair Cost
Can I Still Drive?

What Does The P0566 Code Mean?

Within the vehicle option cruise control, there are many functions. Not only can the operator set a specific vehicle speed, and it be maintained automatically using numerous sensors, switches, modules, among many other components, but you can also modify the speed electronically (i.e. “set – ” & “resume +”), temporarily modify speed while storing previous speed (i.e. passing vehicles, unexpected stopping/slowing), among other things.

Given the fact that most of the functions mentioned in the description of P0566, and related codes (P0565, P0567, P0568, P0569, P0570, etc.), are contained within one switch/component, it should be fairly painless to locate the mechanical inputs (i.e. buttons, switches, talks, etc.) involved. That being said, some of the common names for said component(s) are: Multi-function switch, Steering wheel controls, Cruise control switch, Cruise control module, Accessory switch, etc.

What happened, in this code’s case, is the ECM (Engine Control Module) has detected a malfunction(s) within the signal circuit. Simply put, something went wrong within the circuit of the function mentioned in the description.

When the ECM detects a signal malfunction within one or more of the many cruise control functions, it illuminates the CEL (Check engine light) with P0566 and/or related codes. Most likely, the use of said function will be disabled and/or acting abnormally.

Code P0566 is set when the ECM detects a signal malfunction within the OFF signal of the “On/Off” circuit.

What Are The Symptoms Of The P0566 Code?

Symptoms of a P0566 trouble code may include:

  • Cruise control light in dash not coming on or constant
  • Cruise control inoperative
  • Cannot set cruise control to desired speed or speed is erratic
  • Certain function(s), within the cruise control system, non-operative (i.e. Resume, Set, +, -, Coast, Accel)
  • Commands not functioning consistently

What Are The Potential Causes Of The P0566 Code?

Causes for this P0566 code may include:

  • Cruise control switch, or buttons within the switch, defective and/or damaged
  • Connector(s) not making proper and effective electrical connection
  • Wire(s) within the cruise control harness chafed and/or damaged causing short, open, resistance, etc.
  • Cruise control switch assembly contaminated with fluid (i.e. coffee, soda, juice, etc.)
  • ECM issue
  • Cruise control module defective
  • BCM (Body Control Module) issue
  • Overheated parts causing malfunction

How Serious Is This P0566 Code?

Severity would be considered moderately low. Even if you lose entire functionality of the cruise control system, you can still get to work safely.

As far as further damage if left unattended goes, this would be the rare case in which you may be able to neglect if lets say, your vehicle is old and you can live without cruise, or you cannot afford to fix the vehicle.

That being said, it is possible that neglecting ANY electrical issue long enough may result in further damage.

How Can You Fix The P0566 Code?

Basic Step #1

First thing I would do here, is visually inspect the cruise control switch/module. Sometimes, buttons are missing, cola has stuck the button in one position, buttons are loose and not making proper electrical connections.

That all said, make sure that the buttons, that control the cruise functions, are freely moving and not contaminated with potentially damaging particles and/or dirt. You will also want to record ALL of the cruise functions’ malfunctions or abnormalities.

Basic Step #2

Does the cruise control light come on in the instrument cluster when cruise is manually activated? If not, you may want to verify if there is a fuse for the circuit. This information should be found in the make and model’s service manual. Replace any blown fuses with new and manufacturer-approved ones.

Basic Step #3

To access the harness to the cruise control switch/module, generally speaking, you will need to remove some dash parts (i.e. steering column shroud, airbag module in steering wheel, etc.).

To pinpoint the specific wire involved in the fault, you will definitely be needing a proper wiring harness for your vehicle. These vary significantly, given many reasons. Always acquire proper service information BEFORE executing anything too invasive.

Basic Step #4

It is a good idea to make sure your ABS (anti-lock brakes) system is in good working order and no ABS light on in the dash. ABS uses numerous sensors including speed sensors that, if malfunctioning, could fool the computers into thinking the vehicle is going faster or slower than the actual speed.

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

P0566 Cruise Control Off Signal Malfunction, OBD-Codes.

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