2009 Mercedes-Benz SLK350 Cruise Control Isn't Working

Fixing cruise control issues in the 2009 Mercedes-Benz SLK350

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Reviewed by
Aisha
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 SLK350 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 SLK350 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 initial diagnostic steps to troubleshoot the non-functioning cruise control in a 2009 Mercedes-Benz SLK350?

When troubleshooting the non-functioning cruise control in a 2009 Mercedes-Benz SLK350, it's essential to adopt a methodical diagnostic approach. Begin by checking the cruise control fuse located in the vehicle's fuse box, as a blown fuse can often be the simplest issue to resolve. Next, inspect the cruise control buttons on the steering wheel for any signs of damage or malfunction, as these controls are critical for operation. Following this, verify the functionality of the vehicle's speed sensor, since cruise control relies on accurate speed readings to maintain set speeds. Utilizing a diagnostic scanner to check for error codes can provide insights into any underlying electronic issues. Additionally, ensure that the brake and clutch switches are operational, as faulty switches can disable the cruise control system. It's also wise to examine the wiring connections associated with the cruise control for any loose or damaged wires that could disrupt functionality. Finally, test the cruise control module to confirm it is receiving power and effectively sending signals to engage the system. By systematically addressing these areas, you can effectively diagnose and potentially resolve the cruise control issue in your SLK350.

What are the common problems that could cause the cruise control to stop working in a 2009 Mercedes-Benz SLK350?

When troubleshooting the cruise control system in a 2009 Mercedes-Benz SLK350, it's essential to understand the common problems that may lead to its failure. One of the primary culprits is a faulty brake light switch, which can prevent the cruise control from engaging since it is designed to deactivate when the brake pedal is pressed. Additionally, issues with the speed sensor can disrupt the system's ability to maintain a constant speed, leading to erratic behavior or complete failure. Vacuum leaks in the engine can also impact the cruise control's functionality, causing it to disengage unexpectedly. Furthermore, a defective cruise control module may be responsible for the system's malfunction, as it plays a critical role in controlling the cruise function. Lastly, electrical problems, including faulty wiring or blown fuses, can significantly hinder the operation of the cruise control system. By identifying and addressing these common issues, you can effectively troubleshoot and potentially restore the cruise control functionality in your vehicle.

How urgent is it to repair the non-functioning cruise control in a 2009 Mercedes-Benz SLK350?

Repairing the non-functioning cruise control in your 2009 Mercedes-Benz SLK350 should be considered a priority, albeit not as urgent as critical mechanical failures. The absence of cruise control can compromise safety by increasing driver fatigue and distraction, particularly during long drives where maintaining a consistent speed is essential. Additionally, the comfort of your driving experience is diminished without this feature, as constant speed adjustments can lead to discomfort on extended journeys. From a financial perspective, addressing this issue promptly can help preserve the vehicle's resale value; potential buyers may view a malfunctioning cruise control as a sign of neglect. Furthermore, while the cruise control system may not directly impact the vehicle's mechanical performance, it could indicate underlying problems that, if left unresolved, may escalate into more significant issues. Therefore, while the urgency may not be immediate, timely repair of the cruise control is advisable to ensure safety, comfort, and the overall integrity of your vehicle.

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