Engine-CodesMercury – P1566 Mercury

P1566 Mercury Code - Speed Control Command Switch Out of Range Low

Quick Answer

The P1566 Mercury diagnostic trouble code indicates that the speed control command switch is out of range low. Common causes include Faulty speed control command switch, Damaged wiring or electrical connections, Defective speed control module. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P1566 Mercury indicates Speed Control Command Switch Out of Range Low.
Common causes
Common causes include Faulty speed control command switch, Damaged wiring or electrical connections, Defective speed control module.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Table of contents Created and updated by William Orellana on Aug 25, 2024
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Code P1566 Mercury Description

The P1566 Mercury diagnostic trouble code indicates that the speed control command switch is out of range low. This means that the vehicle's onboard computer has detected a problem with the speed control system, specifically with the command switch that allows the driver to set and adjust the speed control. This issue can affect the vehicle's performance by causing the cruise control system to malfunction or become inoperative. The speed control system helps maintain a constant speed while driving, which can improve fuel efficiency and reduce driver fatigue on long journeys.

OBDII Code P1566 Mercury - Speed Control Command Switch Out of Range Low
P1566 Mercury Code - Speed Control Command Switch Out of Range Low

Common Causes of P1566 Mercury

  1. Faulty speed control command switch
  2. Damaged wiring or electrical connections
  3. Defective speed control module
  4. Malfunctioning vehicle speed sensor
  5. Issues with the throttle position sensor

Symptoms of P1566 Mercury

  1. Inoperative cruise control system
  2. Speed control light illuminated on the dashboard
  3. Unresponsive speed control buttons on the steering wheel
  4. Fluctuating speed control operation
  5. Vehicle surging or hesitation while using cruise control

How to Fix P1566 Mercury

  1. Diagnose the root cause of the issue using a diagnostic scanner
  2. Inspect the speed control command switch for proper functionality
  3. Check the wiring and electrical connections for any damage or corrosion
  4. Test the speed control module and vehicle speed sensor for faults
  5. Replace any faulty components and reset the vehicle's onboard computer to clear the trouble code

Cost to Fix P1566 Mercury

The typical repair costs for addressing a P1566 Mercury code can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. In general, repairing the speed control command switch or related components could range from $100 to $300, including parts and labor. It is advisable to consult with a qualified mechanic or service center for a more accurate estimate based on the vehicle's make and model. Keep in mind that additional diagnostic time may be required to pinpoint the exact cause of the problem before proceeding with repairs.

When is the Code Detected?

The Engine Control Module (ECM) has detected a fault in the cruise control circuit

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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