1991 Mercedes-Benz 300SEL Cruise Control Isn't Working

Fixing Cruise Control Issues in 1991 Mercedes-Benz 300SEL

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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
0%
25% chance it's the
Throttle
0%
20% chance it's
Something else
The most common reasons a 1991 Mercedes-Benz 300SEL 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 1991 Mercedes-Benz 300SEL 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.

What are the initial diagnostic steps to troubleshoot the non-functional cruise control in a 1991 Mercedes-Benz 300SEL?

When troubleshooting the non-functional cruise control in your 1991 Mercedes-Benz 300SEL, start by examining the cruise control actuator, as this component is crucial for the system's operation. Ensure that the linkage is securely connected, as any disconnection can prevent the system from functioning properly. Next, confirm that your specific model is indeed equipped with the cruise control system, as variations in production may lead to differences in features. Additionally, inspect the cruise control fuse, since a blown fuse can disrupt the electrical system and render the cruise control inoperative. By systematically checking these components, you can identify and potentially resolve the issue, making your DIY troubleshooting efforts more effective.

What are the common problems that could cause the cruise control to stop working in a 1991 Mercedes-Benz 300SEL?

When the cruise control in a 1991 Mercedes-Benz 300SEL ceases to function, it can be frustrating, but understanding the common problems can help you diagnose the issue. One frequent culprit is a failed control module, which can disrupt the entire system's operation. Additionally, issues with the throttle actuation can prevent the cruise control from maintaining speed. It's also essential to check for a blown fuse or a defective brake pedal switch, as these components play a critical role in the cruise control's functionality. If the brake lights are not functioning correctly, it may indicate a bad brake switch, which can also interfere with the cruise control system. Lastly, problems with the cruise control amplifier can lead to malfunctions, so inspecting this component is advisable. By systematically checking these areas, you can identify and resolve the issue, restoring your vehicle's cruise control to working order.

How urgent is it to repair the non-functioning cruise control in a 1991 Mercedes-Benz 300SEL?

Repairing the non-functioning cruise control in a 1991 Mercedes-Benz 300SEL is an urgent matter that should not be overlooked. A malfunctioning cruise control system can pose significant safety risks, particularly during long drives where driver fatigue can lead to dangerous situations. Ensuring that all vehicle systems, including cruise control, are operational is crucial for maintaining a safe driving environment. Additionally, a properly functioning cruise control enhances comfort and convenience, allowing drivers to maintain a consistent speed without constant manual adjustments, which is especially beneficial on extended trips. Furthermore, neglecting this repair could indicate underlying issues with other vehicle components, potentially leading to more severe problems and costly repairs down the line. Therefore, addressing the cruise control malfunction promptly is essential for ensuring the safety, comfort, and overall performance of your vehicle.

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Fix 1991 Mercedes-Benz 300SEL Cruise Control Issues