2003 Mercedes-Benz E320 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your 2003 Mercedes-Benz E320 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 2003 Mercedes-Benz E320 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 2003 Mercedes-Benz E320 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.

A faulty cruise control module will simply result in deactivation of cruise control settings. This is because a detected error in the cruise control system could lead to hazardous driving conditions, so the module will be disabled, and the cruise control system warning light will be displayed. This will be a different message depending on make and model, and a warning light or message may be displayed on the driver instrument cluster.

What are the initial diagnostic steps to troubleshoot the non-functional cruise control in a 2003 Mercedes-Benz E320?

When troubleshooting the non-functional cruise control in a 2003 Mercedes-Benz E320, it's crucial to follow a structured diagnostic approach that begins with the simplest checks. Start by inspecting the cruise control fuse in the fuse box; a blown fuse can easily disrupt the entire system. Next, examine the cruise control switch on the steering wheel for any signs of damage or malfunction, as this component is essential for activating the system. After that, check the brake pedal switch, since a faulty switch can prevent the cruise control from engaging, even if other components are functioning correctly. Utilizing a diagnostic scanner to check for error codes can reveal hidden issues that may not be immediately apparent. Finally, ensure that the vehicle speed sensor is working properly, as it plays a critical role in the cruise control's operation. By systematically addressing these areas, you can effectively diagnose and resolve the cruise control malfunction in your vehicle.

What are the common problems that could cause the cruise control to stop working in a 2003 Mercedes-Benz E320?

When the cruise control in a 2003 Mercedes-Benz E320 ceases to function, several common problems may be at play. One of the primary culprits is a faulty brake light switch, which can prevent the system from engaging if it fails to detect when the brake pedal is pressed. Additionally, vacuum leaks within the cruise control system can disrupt its ability to maintain speed, leading to inconsistent performance. Another potential issue is a defective speed sensor, which can provide inaccurate speed readings and cause the cruise control to malfunction. It's also important to check for a blown fuse, as this can completely disable the cruise control system. Throttle-related problems, such as a sticky throttle or issues with the throttle position sensor, can further complicate matters. Lastly, electrical issues, including faulty wiring or connections, can also contribute to the failure of the cruise control system. By systematically addressing these common issues, DIYers can often restore the cruise control functionality in their vehicle.

How urgent is it to address the non-functioning cruise control in a 2003 Mercedes-Benz E320?

Addressing the non-functioning cruise control in a 2003 Mercedes-Benz E320 is important, as neglecting this issue can lead to more significant problems down the line. While the immediate impact on drivability may seem minimal, the cruise control system is integral to the vehicle's overall functionality, particularly during long drives where it enhances comfort and fuel efficiency. A malfunctioning system could signal deeper electronic or sensor issues that might affect other critical components of the vehicle. Moreover, ignoring the problem could result in increased repair costs if the underlying cause worsens over time. Therefore, it is advisable to have the cruise control inspected and repaired promptly to maintain the vehicle's safety and performance, ensuring a reliable driving experience.

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2003 Mercedes-Benz E320 Cruise Control Issues & Repair Costs