Mercedes-Benz SL450 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your Mercedes-Benz SL450 and How to Fix Them

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Reviewed by
Andrew Hajjar
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 SL450 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 SL450 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 SL450

When troubleshooting cruise control issues in your Mercedes-Benz SL450, begin by checking the most accessible components. Start with the brake pedal switch, as a malfunction here can cause the cruise control to deactivate unexpectedly. Ensure that the brake lights are functioning properly; if they are stuck on or not illuminating, this could signal a problem with the switch. Next, inspect the vehicle’s fuses related to the cruise control system, as a blown fuse can disrupt its operation. If these initial checks do not resolve the issue, consider examining the ABS wheel speed sensor and the control module, as these components can also lead to cruise control malfunctions. By following this diagnostic approach, you can systematically identify and address the root cause of the cruise control problems, making your troubleshooting process more efficient and effective.

What Could Cause the Cruise Control to Malfunction in a Mercedes-Benz SL450?

When dealing with a malfunctioning cruise control system in your Mercedes-Benz SL450, it's crucial to understand the common problems that could be at the root of the issue. One of the primary culprits is a faulty control module, which can disrupt the entire cruise control functionality. Additionally, sensor problems, particularly with speed or throttle position sensors, can lead to erratic behavior or complete failure of the system. Mechanical failures, such as issues with the cruise control amplifier or servo unit, may also be responsible for the malfunction. Electrical problems, including faulty wiring or poor connections, can further complicate the situation. Lastly, don't overlook the cruise control button itself; dirt or damage can prevent it from engaging properly. By systematically checking these areas, you can effectively troubleshoot and potentially resolve the cruise control issues in your SL450, ensuring a smoother driving experience.

Why is the Cruise Control Not Working in a Mercedes-Benz SL450?

When the cruise control in your Mercedes-Benz SL450 is not functioning, it is crucial to address the issue promptly, as neglecting it can lead to significant safety risks and further mechanical complications. A malfunctioning cruise control system can stem from various sources, such as a faulty ABS sensor, which not only affects cruise control but also compromises the vehicle's stability and braking systems. Additionally, a defective brake pedal switch can inadvertently disengage cruise control, posing a danger during highway driving. If the cruise control switch itself is malfunctioning, it may lead to unpredictable behavior, making it essential to diagnose and repair the issue. Furthermore, problems with the throttle control system or speed sensors can hinder the cruise control's ability to maintain a steady speed, potentially resulting in erratic driving conditions. Therefore, it is advisable to seek professional assistance to accurately diagnose the problem and ensure your vehicle remains safe and reliable on the road.

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