2009 Mercedes-Benz S550 Cruise Control Isn't Working

Fixing Cruise Control Issues in 2009 Mercedes-Benz S550

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Reviewed by
Bo Fader
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 S550 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 S550 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.

The cruise control switch can cause complete failure of the cruise control feature, but in a lucky scenario only partial functionality will be lost. This means that the cruise control may come on, but that it will not increase in speed automatically, or the cancel button does not work leading the driver to cancel cruise control with the foot brake. In some vehicles, the cruise control light may illuminate, or a warning message may be displayed due to lack of functionality.

What are the steps to diagnose the non-functioning cruise control in a 2009 Mercedes-Benz S550?

To effectively diagnose the non-functioning cruise control in a 2009 Mercedes-Benz S550, it is essential to adopt a systematic diagnostic approach that begins with simpler checks before progressing to more complex assessments. Start by inspecting the cruise control fuse in the fuse box, as a blown fuse is a common issue that can easily be resolved. Next, examine the cruise control buttons on the steering wheel to ensure they are functioning correctly, since any malfunction here can impede the system's operation. Utilizing a diagnostic scanner to check for error codes can provide critical insights into potential electronic issues affecting the cruise control. Following this, inspect the speed sensors, as faulty sensors can disrupt the cruise control's performance. Additionally, assess the brake and clutch switches, as any malfunction in these components can prevent the cruise control from engaging properly. Finally, conduct a thorough inspection of the wiring and connections related to the cruise control system, as loose or damaged wiring can lead to significant operational problems. By following this structured approach, you can efficiently identify and address the root cause of the cruise control malfunction, ensuring a smoother driving experience.

What are the common problems that could cause the cruise control to stop working in a 2009 Mercedes-Benz S550?

When dealing with cruise control issues in a 2009 Mercedes-Benz S550, it's essential to understand the common problems that may be at play. One of the primary culprits is a faulty brake light switch, which can prevent the cruise control from engaging since the system is designed to disengage when the brake pedal is pressed. Additionally, speed sensor issues can disrupt the cruise control's functionality, as the system relies on accurate speed readings to maintain the desired speed. Another potential problem is vacuum leaks, which can interfere with the engine's ability to sustain a constant speed, ultimately affecting cruise control performance. A defective cruise control module may also be responsible for the malfunction, as it is a critical component of the system. Lastly, electrical problems, such as blown fuses or wiring issues, can significantly impact the cruise control's operation. By identifying and addressing these common issues, DIYers can effectively troubleshoot and restore the cruise control functionality in their vehicle.

How urgent is it to address the non-functioning cruise control in a 2009 Mercedes-Benz S550?

Addressing the non-functioning cruise control in a 2009 Mercedes-Benz S550 is crucial for both safety and vehicle performance. When this feature fails, it not only diminishes the convenience of maintaining a steady speed during long drives but may also signal deeper issues within the vehicle's systems. Ignoring the problem can lead to increased driver fatigue, especially on extended trips where cruise control is typically utilized, potentially resulting in dangerous situations on the road. Moreover, a malfunctioning cruise control system could indicate underlying mechanical or electronic faults that, if left unchecked, might escalate into more significant and costly repairs. Therefore, it is advisable to prioritize the inspection and repair of the cruise control system by a qualified mechanic to ensure the vehicle remains safe and reliable for all driving conditions. Taking prompt action not only enhances the driving experience but also safeguards against potential hazards associated with a malfunctioning system.

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