OEM Doctor: On Better Blind Spot Detectors

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If you tried installing an aftermarket blind spot detector a few years ago and were disappointed, it’s time to take a second look at the category.  Newer products are more reliable and easier to install.

Many new microwave blind spot detection system are less likely to false alerts and are better at connecting to the vehicle.  They require less install time. The catch–they are still subject to the expertise of the installer.

I wrote about blind spot technology a few years ago, but since then the market has evolved.  I will give a brief review of the changes and what this Doctor feels you need to know when choosing to carry blind spot detection systems.


Years ago, all aftermarket blind spot detection systems were ultrasonic. Since the launch of microwave technology, ultrasonic has increasingly taken a back seat to microwave.  Here’s a quick review of the difference:

ULTRASONIC is a LINE of SIGHT-based system that sends an invisible radar beam out looking for objects.  It bounces back, measuring the distance of the object by how long it takes for the return signal to be received. Users get an alert via a beep or LED light.

This technology is very reliable when it is programmed to a specific vehicle, so many OEM car manufacturers still use ultrasonic today.  They can control every aspect of the car’s parameters such as bumper height, wheel base, sensor angle, even power consumption for a precise user experience; which is why most don’t upgrade to microwave.

The aftermarket can’t control such parameters. We need a universal system for a number of different vehicle possibilities, hence the reason why we experience false alarms or constant blinking LEDs due to mailboxes, light poles, and more.    This is what ushered in MICROWAVE technology, which was touted as the solution to ultrasonic FALSING issues and faster install times.

MICROWAVE blind spot sensor technology is not line of sight, so it allows a BEHIND THE BUMPER mount; no holes have to be drilled.  It also has a much more refined signal, which reduces the amount of false alarms.

Microwave systems also include cross traffic with some of the newer systems adding both entry and exit zone monitoring as well.

Cross traffic in blind spot detection

Cross traffic—When you are backing out of a parking stall or a driveway, the system will check for oncoming traffic perpendicular left and right of the vehicle’s bumper and issue an alert.   It’s a very convenient feature by the way, especially given how congested and hectic the roads and parking lanes can be.

Entry and Exit Zone Monitoring was originally only available via OEM factory solutions.  This is where the system can monitor a vehicle that is passing you or when you are passing a vehicle.   Many aftermarket systems currently still only monitor when a vehicle passes you.   But a few companies have added this feature.


A blind spot system needs to communicate with your vehicle speed and gear position to ensure features turn on when you need them and off when you don’t.

VSS-This is where the system is designed to connect to the Vehicle Speed Signal wire.  Typically, this wire comes off of the transmission hub and is usually accessible inside the vehicle.   This type of system can be very advantageous for cars that have issues communicating on the other two system types (CAN BUS and GPS).  Manufacturers such as Toyota, Lexus and Subaru benefit from this type of system configuration as the VSS wire is easily tagged and inside the cabin of the vehicle.

GPS-This is where the system uses a GPS antenna to send and receive vehicle speed and direction in order to control the turning on and off of certain features like cross traffic or low speed monitoring.   Although this feature is very universal and does not require technical communication with the car, I have found it to be good at times but also fall short.  Tall buildings, trees, hills and mountains can impede the signal reliability, just as they do in GPS for navigation. Since we’re using it for blind spot monitoring, it seems a bit risky at times but that is just my opinion.

CAN BUS- This is probably the most common.   It is easily accessible as it is typically located on the OBD2 diagnostic connector under the dashboard and provides all of the information the system needs such as reverse, turn signals and more.    In most cases, it is very reliable and usable for a satisfying end result.

The potential side effect, however, is on vehicles mentioned above such as Toyota, Lexus and Subaru whereby the CAN BUS signal information is not consistent or stable enough for an aftermarket system.  It can cause erratic feedback issues..


If you are already installing this type of product, you have likely found a system that you are comfortable with.  Either type is fine.  I myself am a sensor-based person, but I have heard from many that they prefer the license plate frame solution.  Here is my quick two cents:


These types of systems give a very detailed monitoring field and are incredibly accurate.  The limitations though are based on how they are installed.   You may be required to remove some factory paneling.  This adds install time and cost in labor.   But this type of configuration has shown to be the most reliable yet.


In this system the sensors are built into a license plate frame.  It is very quick to install.   The system performs fairly well and works on many vehicles, including trucks. The downside is the location reduces the amount of field sensing on the left and right side of the vehicle.


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1 Comment

  1. Well said!! Love it, as a manufacture love seeing this category grow and have success! Hopefully more dealers, installers, salespeople will get behind this and start making money!

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