1999 Mercedes-Benz SL500 Cruise Control Isn't Working

Fixing Cruise Control Issues in 1999 Mercedes-Benz SL500

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Reviewed by
Devin Cabugcal
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 1999 Mercedes-Benz SL500 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 1999 Mercedes-Benz SL500 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 steps to diagnose the non-functioning cruise control in a 1999 Mercedes-Benz SL500?

To effectively diagnose the non-functioning cruise control in your 1999 Mercedes-Benz SL500, start by performing a basic functionality test of the system. Begin by checking the cruise control switch to ensure it is operational; if it doesn’t engage, this could be the root of the problem. Next, verify that the system disengages when the brake pedal is pressed, as this is a critical safety feature. If the system still does not respond, inspect the wiring and connections for any visible damage or corrosion. If you have access to a STAR SDS system, utilize it for a more in-depth analysis; however, if not, you can manually check the cruise control module and related components for faults. After each step, test the system to see if it engages properly, allowing you to pinpoint the issue more effectively. By following this structured approach, you can systematically identify and resolve the problem with your cruise control system.

What are the common problems that could cause the cruise control to stop working in a 1999 Mercedes-Benz SL500?

When troubleshooting the cruise control system in a 1999 Mercedes-Benz SL500, it's essential to consider several common problems that may be at play. One of the primary culprits is a faulty brake light switch, which can prevent the cruise control from engaging if it fails to signal that the brake pedal has been pressed. Additionally, vacuum leaks within the system can disrupt the cruise control's ability to maintain a steady speed, leading to erratic performance. Another critical component to examine is the speed sensor; if this sensor is defective, it can provide inaccurate speed readings, causing the cruise control to malfunction. Furthermore, issues with the throttle actuator can hinder the system's ability to adjust the throttle position correctly, impacting overall functionality. Lastly, electrical problems, such as blown fuses or damaged wiring, can also interfere with the cruise control system. By understanding these common issues, DIY enthusiasts can better diagnose and address the problems affecting their vehicle's cruise control system.

How urgent is it to address the non-functioning cruise control in a 1999 Mercedes-Benz SL500?

When it comes to the non-functioning cruise control in a 1999 Mercedes-Benz SL500, understanding the urgency of the situation is crucial for any DIY enthusiast. While the malfunction may not pose an immediate safety risk like failing brakes or steering, it is still essential to address the issue promptly. A functioning cruise control system enhances driving comfort, particularly on long trips, by allowing the driver to maintain a steady speed, which can also contribute to better fuel efficiency. Ignoring this problem could lead to increased driver fatigue during extended drives, making it a concern for overall driving experience. Additionally, delaying repairs may result in further complications or inconveniences down the line, potentially affecting the vehicle's resale value. Therefore, while it may not be the most critical repair, taking action to fix the cruise control system is advisable to ensure the vehicle remains in optimal condition and to enhance your driving comfort.

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1999 Mercedes-Benz SL500 Cruise Control Issues & Repairs