Diagnosing Lexus Rx350 Blind Spot Monitor: Step-By-Step Guide

The Lexus RX350 blind spot monitor is a useful feature that enhances driving perception and makes lane changes smoother. When the monitor stops working, it is most likely due to a failed sensor. The blind spot monitoring system uses sensors located around the vehicle to detect obstacles and illuminate a light, alerting the driver. If any of these sensors fail, the system will not work. To diagnose the issue, you can check for system faults using a dealership-level scan tool or clean the sensors, including those on the underside of the side-view mirrors. In some cases, the problem may lie in the electrical system or the remote start function.

Cleaning sensors and bumper terminals

If you are experiencing issues with your Lexus RX350 blind spot monitor, it may be due to dirty sensors and bumper terminals. To clean them, you will need a cleaning solution, such as alcohol, and a cloth.

First, locate the blind spot monitoring sensors. These are usually found on the inside left and right-hand sides of the rear bumper. Check if the sensors and the surrounding areas are covered in dirt, mud, or debris. If so, clean them thoroughly. Be careful when using alcohol as it can remove wax, so use it sparingly. Pay particular attention to the sensors on the rear bumper passenger side, as they may require extra cleaning.

In addition to cleaning the sensors, you can also try cleaning the button sensors located on the front and rear bumpers. Use a small amount of alcohol on a cloth to clean these sensors.

After cleaning the sensors and bumper terminals, restart your vehicle to see if the blind spot monitor is functioning correctly. If the issue persists, you may need to take your vehicle to a Lexus dealer or mechanic for further inspection.

It is important to maintain the cleanliness of the sensors and bumper terminals to ensure the proper functioning of the blind spot monitor. Regular cleaning and maintenance can help prevent issues and ensure the safety of you and other drivers on the road.

Checking for faulty sensors

If your Lexus RX350's blind spot monitor is not working, it is most likely caused by a failed sensor. The blind spot monitoring system uses a series of sensors located around the vehicle to illuminate a light, indicating that another vehicle is in your blind spot. If any of these sensors fail, the system will not work.

You can check the system for any detected faults if you have access to a dealership-level scan tool. You can also try cleaning the sensors, including those on the underside of the side-view mirrors, to see if that solves the problem. If your sensors are dirty or covered with snow or a sticker, the blind spot monitor may not operate, and a warning message will be displayed. In this case, clear off the dirt or snow and drive the vehicle with the operation conditions of the BSM function satisfied for approximately 10 minutes. If the warning message does not disappear, have the vehicle inspected by your Lexus dealer.

The blind spot sensors/detection units are not visible and are located under the bumper corners, one on each side. Try cleaning the button sensors located on the front and rear bumpers. You might have to use some alcohol, but use it sparingly as it will remove wax. Pay particular attention to those on the rear bumper passenger side.

There are two fuse boxes, and both have labels identifying each fuse and what it protects inside the covers. There is one fuse box under the dashboard to the left of the steering wheel, and another under the hood on the driver's side. Check these fuses to see if they are the problem.

Understanding the BSM and RCTA functions

The Blind Spot Monitor (BSM) and Rear Cross Traffic Alert (RCTA) are two functions of the Lexus RX 350L and RX450h's safety system. The BSM function assists the driver in making decisions when changing lanes, while the RCTA function assists the driver when backing up.

The BSM uses radar sensors to detect vehicles travelling in adjacent lanes and alerts the driver to their presence through indicators on the outside rearview mirror. If a vehicle is detected in a blind spot, the outside rearview mirror indicator on that side will illuminate. If the driver then operates the turn signal lever towards the detected side, the indicator will flash.

The RCTA function detects vehicles approaching from the right or left at the rear of the vehicle and alerts the driver through both outside rearview mirror indicators flashing. The RCTA function is only available when the BSM function is turned on.

The BSM and RCTA functions can be turned on or off through the Lexus RX's meter control switches. To do this, press the meter control switch to select the BSM function, then press the meter control switch again to select either the BSM or RCTA function.

It is important to note that the BSM and RCTA functions rely on sensors located on the rear bumper of the vehicle. These sensors should be kept clean and free of debris, snow, or mud to ensure proper functioning. If the sensors are not functioning properly, a warning message will be displayed, and the vehicle should be inspected by a Lexus dealer.

Adjusting mirrors to eliminate blind spots

Adjusting your mirrors correctly can help eliminate blind spots in your Lexus RX350. Here is a step-by-step guide to help you achieve this:

• Start by sitting in the driver's seat and placing your head against the driver's side window.
• Adjust the driver's side mirror so that you can just see the side of your car. This ensures that you eliminate the blind spot on that side.
• Now, lean in the opposite direction, so your head is over the centre console.
• Adjust the passenger side mirror in the same way, so you can just see the side of your car.
• This adjustment technique will significantly reduce your blind spots. However, you won't be able to see directly behind your vehicle with these mirror settings. To check your rear view, use the inside rearview mirror.
• This method takes some getting used to, but it is an effective way to minimise blind spots and enhance your driving experience.
• Remember, even with correct mirror adjustments, always turn your head to check your blind spots before changing lanes.

In addition to mirror adjustments, the Lexus RX350 also offers a Blind Spot Monitor (BSM) system. This uses radar sensors to detect vehicles in adjacent lanes and alerts the driver via indicators on the outside rearview mirror. The BSM system also includes a Rear Cross Traffic Alert (RCTA) function, which assists when backing up and alerts you to objects approaching from the rear.

By combining proper mirror adjustments with the BSM system, you can further enhance your awareness and make lane changes with added confidence.

Identifying common issues and troubleshooting

The Lexus RX350's Blind Spot Monitor (BSM) is a system that has two functions: the BSM function, which assists the driver in making decisions when changing lanes, and the RCTA (Rear Cross Traffic Alert) function, which assists the driver when backing up. These functions use the same sensors.

When the BSM is not functioning, it is most likely caused by a failed sensor. The BSM uses a series of sensors located around the vehicle to illuminate a light and indicate to the driver that there is an object in their blind spot. If any of these sensors fail, the system will not work.

You can try cleaning the sensors, including those on the underside of the side-view mirrors, to see if that solves the problem. If you have access to a dealership-level scan tool, you can check the system for any detected faults.

In some cases, the issue may be related to the electrical system. For example, one user reported that their BSM malfunctioned after a short drive in moderate rain, along with an AWD malfunction warning sign. They discovered that the battery terminals were rusty and, after cleaning them, the issue was resolved except for the BSM.

Another user reported that their BSM issue was caused by a glitch in the electrical system related to the remote start function. If they used the remote start, the driver-side monitor would not work, but if they started the car without the remote, it functioned normally.

It is also important to ensure that the sensors and their surrounding areas are kept clean and free of dirt, snow, or stickers, as this can affect the BSM's operation. If the sensors or their surrounding areas are subjected to a strong impact, it is recommended to have the vehicle inspected by a Lexus dealer.

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