Mercedes-Benz 400SE Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your Mercedes-Benz 400SE 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
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 400SE 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 400SE 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 400SE

When troubleshooting cruise control issues in your Mercedes-Benz 400SE, it's crucial to adopt a methodical diagnostic approach. Start by inspecting the fuse box for any blown fuses related to the cruise control system, as this is often a straightforward fix that can resolve the problem quickly. Next, check the brake light switch; even if the brake lights are functioning, a faulty switch can prevent the cruise control from engaging. If these initial checks do not yield results, examine the ABS wheel speed sensors, as a malfunction here can disrupt not only cruise control but also other critical systems like ABS and stability control. Additionally, inspect the spiral cable in the steering wheel, which is essential for communication between the control switch and the cruise control system. If electrical issues are suspected, ensure that all connectors and wiring are intact. Lastly, if the problem persists, consider more complex components such as the throttle control system or speed sensor, as these can also significantly impact cruise control functionality. By following this structured approach, you can effectively diagnose and address the issues affecting your vehicle's cruise control system.

What Could Cause the Cruise Control to Malfunction in a Mercedes-Benz 400SE?

When dealing with cruise control malfunctions in a Mercedes-Benz 400SE, it's essential to consider several common problems that could be at the root of the issue. One frequent culprit is a defective brake pedal switch, which can prevent the cruise control from engaging properly. Additionally, a dead battery may disrupt the electrical systems, leading to cruise control failure. The ABS wheel speed sensor is another critical component; if it malfunctions, it can interfere with the cruise control's operation. A blown fuse is also a straightforward issue to check, as it can easily disable the system. For older models, a broken vacuum line may be responsible for the malfunction, while newer vehicles might experience issues due to a faulty throttle control system. Furthermore, a bad spiral cable within the steering wheel can disrupt communication between the control switch and the cruise control system. Lastly, any electrical issues, including faulty connectors or engine-related problems, can also impact the cruise control's functionality. By systematically diagnosing these potential issues, DIYers can effectively troubleshoot and resolve cruise control malfunctions in their Mercedes-Benz 400SE.

Why is it Urgent to Fix the Cruise Control in a Mercedes-Benz 400SE?

Fixing the cruise control in a Mercedes-Benz 400SE is not just a matter of convenience; it is an urgent necessity that directly impacts your safety and driving comfort. A malfunctioning cruise control system can lead to erratic speed control, which may increase the risk of accidents, especially during long drives where maintaining a steady speed is crucial. Ignoring symptoms such as unresponsive controls or sudden disengagement can escalate into more significant mechanical failures, potentially resulting in costly repairs and unsafe driving conditions. Moreover, the frustration of dealing with a faulty cruise control can detract from the overall enjoyment of your driving experience, making long trips more stressful than they need to be. Therefore, addressing cruise control issues promptly ensures not only the functionality of this essential feature but also enhances your safety and comfort on the road.

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Mercedes-Benz 400SE Cruise Control Issues & Repair Costs