2018 Mercedes-Benz SLC300 Cruise Control Isn't Working

Fixing cruise control issues in the 2018 Mercedes-Benz SLC300

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Reviewed by
Bo Fader
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 2018 Mercedes-Benz SLC300 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 SLC300 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-functional cruise control in a 2018 Mercedes-Benz SLC300?

When faced with a non-functional cruise control in your 2018 Mercedes-Benz SLC300, start by checking the cruise control fuse, as a blown fuse can often be the simplest issue to resolve. Next, ensure that the cruise control settings are correctly configured according to your vehicle's manual, as incorrect settings can prevent activation. Utilizing a diagnostic scanner to check for error codes can provide insight into any underlying issues that may not be immediately visible. Additionally, inspect the cruise control switch on the steering wheel for any signs of damage or malfunction, as this component is crucial for operation. It's also important to verify that the brake pedal switch is functioning properly, since a faulty switch can inhibit cruise control engagement. Finally, test the vehicle speed sensor to confirm it is accurately relaying speed information to the cruise control system. By systematically addressing these areas, you can effectively diagnose and potentially fix the cruise control issue in your SLC300.

What are the common problems that could cause the cruise control to stop working in a 2018 Mercedes-Benz SLC300?

When troubleshooting cruise control issues in a 2018 Mercedes-Benz SLC300, it's essential to understand the common problems that may be at play. A faulty speed sensor is often the primary culprit, as it plays a crucial role in relaying the vehicle's speed to the cruise control system. If this sensor malfunctions, the system may fail to engage or maintain the desired speed. Additionally, the brake light switch can cause significant disruptions; if this switch is defective, it may not signal the cruise control to disengage when the brake pedal is pressed, leading to operational failures. Another potential issue is the throttle actuator, which regulates the engine's throttle opening. If it malfunctions, the cruise control may struggle to maintain speed effectively. Electrical problems, such as blown fuses or wiring issues, can also hinder the cruise control's functionality, as can vacuum leaks within the system. By systematically checking these components, DIY enthusiasts can identify and potentially resolve the issues affecting their cruise control system, restoring its functionality and enhancing their driving experience.

How urgent is it to address the non-functioning cruise control in a 2018 Mercedes-Benz SLC300?

When it comes to the non-functioning cruise control in your 2018 Mercedes-Benz SLC300, understanding the urgency of the situation is crucial for both safety and vehicle performance. While it may not seem like an immediate emergency, neglecting this issue can lead to more significant problems down the line. A malfunctioning cruise control system can indicate underlying issues within the vehicle's electronic or mechanical systems, which, if left unaddressed, could compromise your driving experience and safety. For DIY enthusiasts, it’s essential to recognize that the cruise control system is not just a convenience; it plays a vital role in maintaining consistent speed, reducing driver fatigue, and enhancing fuel efficiency during long drives. Therefore, if you notice any irregularities, such as the system not engaging or disengaging unexpectedly, it’s advisable to conduct a thorough inspection or consult a professional. Addressing these symptoms promptly can prevent further damage and ensure that your vehicle remains safe and reliable on the road.

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2018 Mercedes-Benz SLC300 Cruise Control Issues & Solutions