2009 Mercedes-Benz SL550 Cruise Control Isn't Working

Fixing Cruise Control Issues in the 2009 Mercedes-Benz SL550

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Reviewed by
Andrew Hajjar
Written by RepairPal Car Genius
Updated January 14, 2025
0%
30% chance it's the
Sensor
0%
25% chance it's the
Control Module
0%
25% chance it's the
Throttle
0%
20% chance it's
Something else
The most common reasons a 2009 Mercedes-Benz SL550 cruise control isn't working are failed control module, sensor or switch issues, or throttle actuation problems.
  • Sensor: A faulty or malfunctioning sensor can lead to incorrect readings, causing issues with engine performance or other systems relying on accurate data.
  • Control Module: A faulty control module can lead to erratic vehicle behavior or failure of various electronic systems due to improper signal processing.
  • Throttle: A faulty throttle body or a defective accelerator pedal position sensor may be causing inconsistent throttle response.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2009 Mercedes-Benz SL550 cruise control isn't working?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

In the event that a wheel speed sensor fails, the ABS, traction control system (TCS) and manufacturer specific stability control system lights will illuminate, informing the driver that the systems are disabled. The vehicle will be more prone to tire slip, and normal driving patterns may need to be adjusted to correct for the loss of computer control. On older vehicle's, the speedometer can be affected, causing illumination of the check engine light as well.

What are the initial diagnostic steps to troubleshoot the non-functioning cruise control in a 2009 Mercedes-Benz SL550?

When troubleshooting the non-functioning cruise control in a 2009 Mercedes-Benz SL550, it's essential to adopt a systematic diagnostic approach. Start by checking the cruise control fuse, as a blown or damaged fuse can easily disrupt the system's functionality. Next, inspect the cruise control switch located on the steering wheel to ensure it is operating correctly; a malfunctioning switch can prevent the system from engaging. It's also crucial to verify that the brake lights are functioning properly, as a faulty brake light switch can inadvertently disable the cruise control. Additionally, examine the vehicle's speed sensors to confirm they are working and providing accurate data, as these sensors are vital for the cruise control system's operation. Finally, scanning the vehicle's onboard computer for any error codes can help identify specific issues related to the cruise control system. By following these steps, you can effectively diagnose and address the problem, potentially saving time and money on repairs.

What are the common problems that could cause the cruise control to stop working in a 2009 Mercedes-Benz SL550?

When the cruise control in a 2009 Mercedes-Benz SL550 ceases to function, several common problems may be at play. One of the primary culprits is a faulty brake light switch, which is crucial for the cruise control system as it disengages the cruise when the brake pedal is pressed. If this switch malfunctions, it can prevent the cruise control from engaging at all. Another potential issue is related to the speed sensor; if this component fails to provide accurate speed readings, the cruise control system cannot operate correctly. Additionally, vacuum leaks within the cruise control system can disrupt its functionality, leading to unexpected disengagement or failure to engage. A defective cruise control module may also be responsible for the malfunction, as it is the central unit that controls the system's operations. Lastly, electrical problems, such as blown fuses or damaged wiring, can significantly impact the cruise control's performance. By understanding these common issues, DIYers can effectively troubleshoot and resolve the cruise control problems in their SL550, restoring the convenience of this feature.

How urgent is it to address the non-functioning cruise control in a 2009 Mercedes-Benz SL550?

When it comes to the non-functioning cruise control in a 2009 Mercedes-Benz SL550, understanding the urgency of the situation is crucial for any DIY enthusiast. While the immediate safety risks may not be as pronounced as with other critical vehicle components, neglecting this issue can lead to a cascade of problems. A malfunctioning cruise control system can disrupt the vehicle's electrical network, potentially affecting other systems and leading to more significant repairs down the line. Moreover, the convenience of cruise control, which aids in maintaining a steady speed and reducing driver fatigue, is a valuable feature that enhances the driving experience, especially on long journeys. Therefore, while it may not be an emergency, addressing the non-functioning cruise control promptly is advisable to ensure the vehicle operates at its best and to prevent further complications that could arise from delayed repairs. Taking action sooner rather than later will help maintain the overall performance and safety of your SL550.

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