P0566: Cruise control master switch OFF signal malfunction
Cruise control master switch OFF signal malfunction
Severity: Severity not verified — if the car runs badly, have it inspected
The sources sampled define the code but do not rate urgency. It concerns the cruise control switch signal, so the usual effect is cruise control not working, but that is not stated by the sources.
P0566 in short
P0566 means the cruise control master switch OFF signal is malfunctioning. TroubleCodes.net lists the master switch, wiring in the circuit and the engine computer as the possible causes. Inspect the switch and wiring first. Basic scan tools can read the code, and one that tests components helps narrow it down.
The Delaware DMV list titles P0566 Cruise Control Off Signal Malfunction, and TroubleCodes.net describes it as the cruise control master switch OFF signal circuit.
TroubleCodes.net lists wiring, the master switch and the ECM as fault locations. It has not published a fuller guide, so start with the cheapest checks: the switch connector and wiring.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Faulty cruise control master switch
Common general cause- Why it ranks here
- TroubleCodes.net lists the master switch among the three causes, and it is the part that produces the OFF signal.
- What would change this
- Rises if the switch does not give a clean reading on a scan tool or meter. Falls if the signal changes correctly when the switch is pressed.
Cause 2: Damaged or corroded wiring in the switch circuit
Common general cause- Why it ranks here
- TroubleCodes.net lists wiring first, and a break or corrosion in the circuit sends the computer the wrong signal.
- What would change this
- Rises if the harness or connector is damaged or corroded. Falls if the wiring checks good.
Cause 3: Engine computer fault
Possible — needs testing- Why it ranks here
- TroubleCodes.net lists the ECM last; test the switch and wiring first because they are more likely.
- What would change this
- Rises only if the switch and wiring both test good.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all stored codes and note whether any other cruise control or brake switch codes are stored.
IfOnly this cruise control code is stored
It meansInspect the cruise switch and its wiring.
Step 2: Look at the cruise control master switch and its connector for damage, looseness and corrosion, and check the switch reading with a scan tool or meter.
IfConnector or wiring is damaged or corroded
It meansRepair the wiring.
IfThe switch reading does not change correctly
It meansThe switch is likely faulty.
IfSwitch and wiring check good
It meansThe computer is the remaining suspect; have a shop confirm.
Symptoms
- Check engine light on
How to fix
On your vehicle
We don't have reviewed vehicle-specific evidence for P0566 yet. The causes and tests above apply across vehicles.
Related codes
No curated relationships for P0566 yet.
P0566 questions
What does P0566 mean?
The cruise control master switch OFF signal is malfunctioning, per the Delaware DMV list and TroubleCodes.net.
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
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