BMW 840i XDrive Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your BMW 840i xDrive and How to Fix Them

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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
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25% chance it's the
Throttle
0%
20% chance it's
Something else
The most common reasons a BMW 840i xDrive 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 BMW 840i xDrive 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.

Troubleshooting Cruise Control Issues in a BMW 840i xDrive

When troubleshooting cruise control issues in your BMW 840i xDrive, it's essential to adopt a systematic diagnostic approach. Begin by checking the simplest potential causes, such as inspecting the fuse related to the cruise control system, as a blown fuse can often be the culprit behind its malfunction. Next, examine the brake pedal switch, since a failing switch can disrupt the cruise control's operation. If these initial checks do not resolve the issue, proceed to test the wheel speed sensors and the ABS control module using a multimeter to assess their functionality. These components are critical for the cruise control system's performance, and any faults here may require more in-depth diagnostics or professional assistance. By following this structured approach, you can efficiently identify and address the root cause of your cruise control problems, potentially saving time and money on repairs.

What to Check When Cruise Control Isn't Working in a BMW 840i xDrive?

When your cruise control isn't functioning in a BMW 840i xDrive, it's essential to systematically check several key components to identify the root cause of the issue. Start by inspecting the fuse related to the cruise control system, as a blown fuse is a common culprit. Next, evaluate the control module, sensors, and switches, as failures in these areas can disrupt the cruise control's operation. Additionally, consider the throttle actuation system; a malfunctioning throttle position sensor may prevent the cruise control from engaging properly. It's also important to examine the SZL unit and the wiring in the steering wheel, as any damage here could lead to failures. Don't overlook the radar surface; ensure it is clean, as dirt can interfere with the system's functionality. Furthermore, check the brake switch and brake lights, since issues with these components can inadvertently disable cruise control. For older models, the EML system may also be a factor. Lastly, inspect the actuator gear wheel for any missing teeth and ensure the speed sensor is functioning correctly, as both can significantly impact cruise control performance. By methodically checking these areas, you can effectively troubleshoot and resolve the cruise control issues in your BMW 840i xDrive.

Why is the Cruise Control Not Working in a BMW 840i xDrive?

When the cruise control system in your BMW 840i xDrive fails, it’s crucial to understand the urgency of the situation. Ignoring symptoms such as unresponsive controls or erratic behavior can lead to more significant problems, including potential safety hazards while driving. Common issues like a malfunctioning control module, faulty sensors, or a defective throttle position sensor can disrupt the system's functionality, causing the engine to behave unpredictably. For instance, a failed throttle position sensor may lead to excessive fuel consumption and black exhaust, indicating that the engine is overcompensating. Additionally, dirty or malfunctioning speed sensors can prevent the cruise control from engaging properly, further complicating your driving experience. Addressing these issues promptly not only ensures your vehicle operates smoothly but also enhances your safety on the road. Regular maintenance and timely repairs are essential to prevent these problems from escalating, allowing you to enjoy a seamless driving experience in your BMW 840i xDrive.

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