Mercedes-Benz 350SDL Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your Mercedes-Benz 350SDL 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
0%
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 350SDL 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 350SDL 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.

Troubleshooting Cruise Control Issues in a Mercedes-Benz 350SDL

When addressing cruise control issues in your Mercedes-Benz 350SDL, it's crucial to adopt a systematic diagnostic approach. Start by checking the simplest components, such as the brake light switch, which can inadvertently disable the cruise control if malfunctioning. Next, utilize a diagnostic scanner to retrieve any fault codes that may provide insight into electronic or mechanical failures. Conduct a visual inspection of the cruise control system, focusing on the cruise control switch and module to ensure they are functioning correctly. If you encounter intermittent issues, where the cruise control activates and then drops out, this may indicate deeper electronic problems that require further investigation. Additionally, inspect the Cruise Control Controller for cold solder connections, as these can often be repaired with a simple reflow of the solder. By following these steps, you can effectively diagnose and resolve cruise control issues, ensuring a smoother driving experience.

What Could Cause the Cruise Control to Malfunction in a Mercedes-Benz 350SDL?

When dealing with cruise control malfunctions in a Mercedes-Benz 350SDL, it's essential to understand the common problems that may arise. One frequent issue is a malfunctioning control module, which can disrupt the system's ability to maintain speed. Additionally, faulty speed sensors, whether located on the wheels or within the transmission, can prevent the cruise control from functioning correctly. Another potential culprit is a defective brake pedal switch; if this switch fails, it may signal the system to disengage unexpectedly. Other factors, such as a dead battery or a malfunctioning ABS wheel speed sensor, can also contribute to cruise control issues. To effectively diagnose these problems, using a diagnostic scanner to retrieve fault codes is crucial, along with a thorough visual inspection of the cruise control components. Testing the cruise control switch and module for proper functionality can help identify whether replacements are necessary, empowering DIYers to tackle the repair confidently.

Why is the Cruise Control Not Working in a Mercedes-Benz 350SDL?

When the cruise control in your Mercedes-Benz 350SDL is not functioning, it is crucial to address the issue promptly, as neglecting it can lead to safety risks and potentially more significant vehicle damage. A defective brake pedal switch is a common culprit, as it can prevent the cruise control from engaging properly. Additionally, a dead battery or a malfunctioning ABS wheel speed sensor may also disrupt the system's functionality. Other factors, such as a blown fuse or problems within the throttle control system, can further complicate the situation. For older models, a broken vacuum line might be the reason behind the malfunction. Moreover, if your vehicle displays an ESP error, it could automatically disable the cruise control, often linked to issues with the brake light switch or wheel speed sensor. Given the complexity of these systems, it is advisable to seek professional inspection and repair to ensure your vehicle remains safe and reliable on the road.

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