1994 Mercedes-Benz E420 Cruise Control Isn't Working

Fixing Cruise Control Issues in 1994 Mercedes-Benz E420

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Reviewed by
Aisha
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 1994 Mercedes-Benz E420 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 1994 Mercedes-Benz E420 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 1994 Mercedes-Benz E420?

When troubleshooting the non-functional cruise control in a 1994 Mercedes-Benz E420, it's essential to adopt a systematic diagnostic approach. Start by checking the fuse box for any blown fuses that may disrupt the cruise control system's operation. If the fuses are intact, inspect the cruise control switch located on the steering wheel to ensure it is functioning correctly, as a faulty switch can prevent engagement. Next, verify the cruise control module's condition, checking for power and proper functionality. It's also crucial to examine the vacuum lines connected to the system for any leaks or damage, as these can significantly impact performance. Additionally, test the brake pedal switch to ensure it is not stuck or malfunctioning, since a faulty switch can inhibit cruise control activation. Finally, check the vehicle speed sensor, as it is vital for the cruise control system to operate effectively. By following these steps in order, you can efficiently diagnose and address the issues affecting your cruise control system.

What are the common problems that could cause the cruise control to stop working in a 1994 Mercedes-Benz E420?

When dealing with cruise control issues in a 1994 Mercedes-Benz E420, it's essential to understand the common problems that may arise. One of the primary culprits is a faulty brake light switch, which can prevent the cruise control from engaging, as this switch is designed to disengage the system when the brakes are applied. Additionally, vacuum leaks within the cruise control system can disrupt its functionality, often stemming from worn hoses or loose connections. Another significant factor could be a defective cruise control module, which is crucial for the system's operation. Speed sensor malfunctions can also hinder the cruise control's ability to maintain a steady speed, while electrical problems, such as blown fuses or wiring issues, can further complicate matters. Lastly, a damaged or misadjusted throttle cable can impact the system's performance. By identifying and addressing these issues, DIYers can effectively troubleshoot and restore the cruise control functionality in their vehicle.

How urgent is it to repair the non-functioning cruise control in a 1994 Mercedes-Benz E420?

When evaluating the urgency of repairing the non-functioning cruise control in a 1994 Mercedes-Benz E420, it is essential to recognize the implications of neglecting this issue. While it may not seem as critical as other mechanical failures, the absence of cruise control can significantly impact driving safety and comfort. Without this feature, drivers may experience increased fatigue during long trips, leading to distractions that could compromise road safety. Additionally, the comfort of maintaining a steady speed is lost, making extended drives less enjoyable. From a financial perspective, addressing the cruise control issue promptly can help preserve the vehicle's resale value; potential buyers often view non-functional features as red flags. Furthermore, the malfunctioning cruise control could indicate underlying mechanical problems that, if left unresolved, may escalate into more significant issues over time. Therefore, while the urgency may not be immediate, timely repair of the cruise control system is advisable to ensure a safer, more comfortable driving experience and to protect the vehicle's overall value.

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