Lexus RX300 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your Lexus RX300 and How to Fix Them

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Reviewed by
Aisha
Written by RepairPal Car Genius
Updated January 14, 2025
0%
30% chance it's the
Sensor
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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 Lexus RX300 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 Lexus RX300 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.

When the vehicle speed sensor fails or the wiring harness prevents signal transmission, the speedometer is the first thing that will stop functioning properly. This can be an intermittent issue where the speedometer only works occasionally, the speedometer may cease all function, or the speedometer may read erratically or incorrectly. Also, the traction control and anti lock brake warning lights specific to each vehicle may be illuminated, depending on the design of those systems. You may notice the vehicle hesitate to accelerate, cruise control will not function properly, and the vehicle may not shift properly through all of the gears.

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.

If the cruise control refuses to turn on at all, the actuator could be at fault. Likewise, if the cruise control stays on but does not maintain a consistent speed, the problem could be a bad actuator. In extreme cases, a malfunctioning actuator could cause the throttle to stick and prevent the vehicle from slowing down. These symptoms may point to a bad actuator. They may also point to other problems with the cruise control and related systems.

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.

A faulty cruise control module will simply result in deactivation of cruise control settings. This is because a detected error in the cruise control system could lead to hazardous driving conditions, so the module will be disabled, and the cruise control system warning light will be displayed. This will be a different message depending on make and model, and a warning light or message may be displayed on the driver instrument cluster.

Troubleshooting Cruise Control Issues in a Lexus RX300

When troubleshooting cruise control issues in your Lexus RX300, begin by checking the simplest components first, such as the cruise control switch located on the steering column. Ensure that the switch is functioning properly, as faulty contacts can prevent the system from engaging. Next, inspect the control module, which is essential for the cruise control's operation; if it appears damaged or unresponsive, it may need replacement. Additionally, examine the sensors that provide critical input to the system, as a malfunctioning sensor can lead to erratic behavior. Don't overlook the throttle, as issues here can disrupt the cruise control's ability to maintain speed. Finally, consider other potential causes such as wiring harness problems or vacuum line issues connected to the cruise control servo. By methodically checking these components, you can effectively diagnose and resolve cruise control problems in your Lexus RX300, ensuring a smoother driving experience. If issues persist after these checks, seeking assistance from a professional mechanic may be necessary for a thorough evaluation.

What Could Cause the Cruise Control to Malfunction in a Lexus RX300?

When dealing with a malfunctioning cruise control system in a Lexus RX300, it's essential to understand the common problems that could be causing the issue. One of the primary culprits is a failed control module, which can disrupt the entire system's functionality. Additionally, faulty sensors or switches may prevent the cruise control from engaging properly. Throttle actuation problems can also arise, particularly in older models where mechanical components may have deteriorated over time. If the cruise control switch itself is defective, or if there are issues with the wiring harness, these can lead to intermittent or complete failure of the system. Another critical aspect to check is the brake light operation; if the brake lights remain illuminated, it could indicate a faulty switch or a broken vacuum line to the cruise control servo, both of which can prevent the cruise control from functioning as intended. By identifying these common problems, DIY enthusiasts can better diagnose and address the issues affecting their Lexus RX300's cruise control system.

Why is the Cruise Control Not Working in a Lexus RX300?

When the cruise control in your Lexus RX300 fails, it’s crucial to address the issue promptly, as neglecting it can lead to safety risks and potentially more significant vehicle damage. Common culprits include a malfunctioning control module, sensor, or switch, which can disrupt the system's functionality. Additionally, problems with throttle actuation or the engine control unit (ECU) may prevent the cruise control from engaging properly. It’s also essential to inspect the cruise control switch and wiring harness for any faults, as these components are vital for the system's operation. Furthermore, a faulty brake light switch or damaged vacuum line can trigger cruise control failure, making it imperative to check these elements as well. By diagnosing and resolving these issues quickly, you not only ensure your safety on the road but also maintain the overall health of your vehicle, preventing more costly repairs down the line.

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