2018 Mercedes-Benz GLS550 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your 2018 Mercedes-Benz GLS550 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 2018 Mercedes-Benz GLS550 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 2018 Mercedes-Benz GLS550 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 steps should I take to diagnose the cruise control issue in my 2018 Mercedes-Benz GLS550?

To diagnose the cruise control issue in your 2018 Mercedes-Benz GLS550, begin with the simplest checks to avoid unnecessary complications. Start by inspecting the cruise control fuse; a blown fuse is a common culprit that can easily be replaced. Next, examine the cruise control buttons on your steering wheel to ensure they are functioning correctly, as faulty buttons can disrupt the system's operation. If these initial checks do not resolve the issue, utilize an OBD-II scanner to identify any error codes that may indicate specific problems within the cruise control system. Pay close attention to the speed sensors, as they are vital for maintaining speed; ensure they are operational. Additionally, check the brake and clutch switches, as malfunctioning switches can prevent the cruise control from engaging. Finally, inspect the wiring connections for any signs of damage or corrosion, which can impede the system's functionality. If these steps do not lead to a solution, it may be time to consult a professional mechanic for a comprehensive diagnosis. By following this structured approach, you can effectively troubleshoot and potentially resolve the cruise control issue in your vehicle.

What are the common problems that could cause the cruise control to stop working in a 2018 Mercedes-Benz GLS550?

When the cruise control in a 2018 Mercedes-Benz GLS550 ceases to function, several common problems may be at play. One of the primary culprits is a faulty speed sensor, which can disrupt the system's ability to accurately gauge the vehicle's speed, preventing it from engaging or maintaining the desired speed. Additionally, issues with the brake light switch can lead to unexpected disengagement of the cruise control when the brake pedal is pressed, creating further frustration for drivers. Another potential issue is a malfunctioning throttle actuator, which can hinder communication between the cruise control system and the engine, ultimately affecting its performance. Furthermore, a defective cruise control module may fail to receive the necessary signals for operation, rendering the system inoperative. Lastly, various electrical problems, such as wiring issues or blown fuses, can also interfere with the cruise control's functionality. By understanding these common problems, DIY enthusiasts can better diagnose and address the issues affecting their vehicle's cruise control system.

How urgent is it to address the malfunctioning cruise control in a 2018 Mercedes-Benz GLS550?

When it comes to a malfunctioning cruise control in a 2018 Mercedes-Benz GLS550, the urgency of addressing the issue cannot be overstated. A faulty cruise control system can lead to unpredictable vehicle behavior, such as sudden acceleration or deceleration, which poses a significant safety risk not only to the driver but also to other road users. For DIY enthusiasts, understanding the potential consequences of neglecting this issue is crucial. Promptly diagnosing and repairing the malfunction ensures that the vehicle's systems operate smoothly, maintaining both safety and performance. Additionally, addressing the problem early can prevent it from escalating into more severe and costly repairs, ultimately saving time and money. Ignoring the symptoms may lead to discomfort during long drives, detracting from the overall driving experience. Therefore, if you notice any irregularities with your cruise control, it is advisable to take action immediately to safeguard your vehicle and ensure a safe driving environment.

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