Mercedes-Benz SLK350 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your Mercedes-Benz SLK350 and How to Fix Them

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Reviewed by
Aisha
Written by RepairPal Car Genius
Updated January 14, 2025
0%
30% chance it's the
Sensor
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25% chance it's the
Control Module
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25% chance it's the
Throttle
0%
20% chance it's
Something else
The most common reasons a 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 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.

Troubleshooting Cruise Control Issues in a Mercedes-Benz SLK350

When troubleshooting cruise control issues in your Mercedes-Benz SLK350, it's essential to adopt a methodical diagnostic approach. Start by checking the ABS sensors, as a malfunctioning wheel speed sensor can disable not only the cruise control but also other critical systems like ABS and stability control. Next, inspect your tires for uneven wear and ensure they are properly inflated, as discrepancies can confuse the vehicle's computer and disrupt cruise control functionality. If these initial checks do not reveal the problem, examine the brake pedal switch, which is a common culprit in older models; a defective switch can falsely signal that the brakes are engaged. Additionally, for older vehicles, assess the vacuum actuator and associated hoses or cables, as damage to these components can hinder cruise control operation. Lastly, verify that the brake lights are functioning correctly, as a faulty brake light switch can trick the system into thinking the brakes are applied. By following this structured approach, you can effectively diagnose and potentially resolve cruise control issues, ensuring a smoother driving experience.

What Could Cause the Cruise Control to Malfunction in a Mercedes-Benz SLK350?

When diagnosing cruise control malfunctions in a Mercedes-Benz SLK350, it's essential to consider several common problems that may be at play. A failed control module, sensor, or switch can often be the root cause, as these components are critical for the system's operation. Additionally, throttle actuation issues may prevent the cruise control from engaging or maintaining speed. Another frequent culprit is a defective brake pedal switch, which can inadvertently signal the system to disengage. Furthermore, the ABS wheel speed sensor plays a vital role in cruise control functionality; any issues here can trigger warning lights and disrupt the system's performance. Environmental factors, such as wet conditions, can also lead to error messages like "Cruise Control Inoperative," while driver error, such as accidentally pressing the accelerator instead of the brake, can complicate matters. Regular maintenance and prompt troubleshooting are crucial to address these issues effectively, ensuring that your cruise control system operates smoothly and reliably.

Why is the Cruise Control Not Working in a Mercedes-Benz SLK350?

When the cruise control in your Mercedes-Benz SLK350 is not functioning, it is crucial to address the issue without delay. Ignoring symptoms such as a malfunctioning brake pedal switch, a blown fuse, or warning messages like "cruise control and speedtronic inoperative" can lead to more significant safety risks while driving. A faulty cruise control system may not only affect your driving comfort but could also indicate underlying problems with the vehicle's electrical or throttle control systems. For instance, if the cruise control intermittently drops out, it may suggest electronic or mechanical failures that could compromise your vehicle's performance. Additionally, issues like a check engine light or problems with the ABS wheel speed sensor can further complicate the situation, potentially leading to costly repairs if left unaddressed. Therefore, it is advisable to diagnose and resolve these issues promptly, either through DIY troubleshooting or by consulting a professional service team, to ensure your vehicle remains safe and reliable on the road.

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