1990 Mercedes-Benz 300CE Cruise Control Isn't Working

Fixing Cruise Control Issues in 1990 Mercedes-Benz 300CE

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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 1990 Mercedes-Benz 300CE 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 1990 Mercedes-Benz 300CE 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 1990 Mercedes-Benz 300CE?

To effectively troubleshoot the non-functional cruise control in your 1990 Mercedes-Benz 300CE, start by checking the speedometer, as it plays a crucial role in the cruise control system's operation. A malfunctioning speedometer can prevent the cruise control from receiving the necessary speed signal, rendering it inoperative. Next, inspect the check engine light; if it is illuminated, it may indicate underlying issues that could affect the cruise control functionality. Utilizing an OBD2 scan tool can help you diagnose any trouble codes associated with the check engine light, providing further insight into potential problems. By systematically addressing these initial checks, you can efficiently narrow down the causes of the cruise control malfunction and determine the next steps for repair.

What are the common problems that could cause the cruise control to stop working in a 1990 Mercedes-Benz 300CE?

When dealing with cruise control issues in a 1990 Mercedes-Benz 300CE, it's essential to understand the common problems that may arise. One of the primary culprits is a defective brake pedal switch, which can disrupt the cruise control's ability to engage or maintain speed. This switch is crucial because it signals the cruise control system when the brakes are applied, and if it malfunctions, the system may deactivate unexpectedly. Additionally, a dead battery or faulty components within the cruise control system can lead to operational failures. Sensors that monitor vehicle speed or other critical functions may also be at fault, preventing the cruise control from working correctly. For DIY enthusiasts, checking these components can be a straightforward process, often involving visual inspections and simple electrical tests to identify and rectify the underlying issues, ultimately restoring the cruise control functionality in your vehicle.

How urgent is it to address the non-functioning cruise control in a 1990 Mercedes-Benz 300CE?

Addressing the non-functioning cruise control in a 1990 Mercedes-Benz 300CE should not be overlooked, as neglecting this issue can lead to more significant problems down the line. While it may not seem like an immediate emergency, a malfunctioning cruise control system can indicate deeper issues within the vehicle's electronic and mechanical systems, such as problems with the control module, sensors, or throttle actuation. These underlying issues could compromise the vehicle's overall performance and safety, potentially leading to erratic driving behavior or even failure of other critical systems. Moreover, if the cruise control system is displaying warning messages, it signals that the system is completely inoperative, which can detract from the driving experience and increase driver fatigue on long journeys. Therefore, it is advisable to address this issue promptly to ensure not only the convenience and comfort that cruise control offers but also to maintain the vehicle's integrity and safety on the road.

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