Seeing in Reverse

Backup-alert systems can help to prevent damage and serious injuries.

Drivers of SUVs, trucks, minivans and other large vehicles know that backing up can be dangerous when it’s hard to see what’s behind you. And when you consider that minivan, truck and SUV sales account for more than half of all automotive purchases in the United States, you can quickly see the enormous potential for accidents.

You can decrease the likelihood of being involved in a back-over accident by installing a backup-warning system. Many types and brands are available, and all are easy to install. Besides protecting children and pets who might accidentally wander behind you, these devices can also help to prevent you from backing into stationary objects that can damage your vehicle.


To help avoid backing into unseen obstacles, children and pets, install an obstacle-sensing system or a backup camera in your vehicle.

Obstacle-sensing technology
If you’re looking for a simple-to-install, inexpensive option for detecting objects behind your vehicle, a passive obstacle-sensing system may be the answer. These systems use rear-mounted sensors to detect objects and then transmit a warning to the driver via a small blinking indicator light and an alert tone. Obstacle-sensing systems use two basic types of technology:

  • Ultrasonics – Among the first types of backup-alert systems that entered the market these use ultrasonic sensors to detect obstacles. A ceramic chip in a polarized electric field sends out and receives a high-frequency sound wave that measures the distance between the vehicle and any obstacles behind it. Ultrasonic systems are generally the most sensitive of the obstacle-sensing units, but their performance can be hindered by rain, snow, strong winds or other inclement weather.
  • Microwave - Sensors that use microwave-based technology rather than ultrasonics are generally not affected by weather. However, one drawback to microwave technology is that the obstacle or the vehicle on which the backup-alert system is mounted must be moving for the microwaves to detect the obstacle — you must begin backing up before the system detects a stationary object such as a tricycle left in the driveway.


Obstacle-sensing systems rely on sensors that are mounted either behind or below the rear bumper.


Some camera-based backup systems such as the Rostra RearSight shown here use a small LCD screen that’s integrated into the rearview mirror.

Although a NHTSA study reported that microwave and ultrasonic obstacle-sensing systems can greatly aid in detecting objects behind a vehicle, none of the sensor-based units tested were able to consistently detect all objects or people in all locations in the blind zone behind a vehicle. All of the sensor-based systems’ detection ranges contained “holes” where children were not detected. Most could detect a child at a range of 4 to 11 ft. away and in areas where the driver would have been otherwise unable to see.

Visual-technology solutions
A step above the simple obstacle-sensing systems’ audible and signal-light alerts, visual systems employ a rear-mounted camera linked to a dashboard monitor. The camera’s image is typically displayed on a small LCD screen that’s integrated into the vehicle’s windshield-mounted rearview mirror or linked with a GPS navigation screen or a separate video screen that can be positioned almost anywhere in the vehicle.

Visual systems are more expensive ($500 to $900, depending on the kit) but are just as easy to install as the simple obstacle-sensing systems. As an added bonus, some visual systems can be linked to a backseat monitor to help you keep an eye on passengers.

All of the camera-based systems the NHTSA tested were able to display nearly the entire rear zone of a vehicle. Under most environmental conditions, the image quality was clear enough that drivers could easily recognize an object or person behind the vehicle.

What’s right for you?
No matter what type of system you choose, consider these factors when deciding on a specific model:

  • Know how the device mounts on your vehicle. Because camera and sensor systems that are mounted on the vehicle’s bumper or body may require drilling holes, they may not be the best choice if you lease your vehicle.
  • If you have a hitch, consider a model that mounts in the trailer-hitch receiver. Though you’ll need to remove the sensor while towing, this option doesn’t require you to drill into the vehicle.
  • Some camera and sensor models mount on the license-plate frame, but some states prohibit these systems because they may obscure the license plate.

Typical Rear-View Camera Installation

To begin installation of a camera-based system, start by drilling a hole for the rear camera; then insert the camera into the hole. (We used a GMC Sierra for our installation; the location of the camera depends on the make and model of your vehicle.)


After inserting the camera into its mounting hole, drill a second hole through the side of the tailgate for the routing of the camera’s wiring harness.


Drill a hole through the side of the tail-light recess for the camera’s wiring harness (note the main wiring harness coming through the tail-light recess) and attach the camera’s harness to the main wiring harness.


After running the wiring harness along the frame rail and through a stock wiring-harness hole into the cab, route the harness behind the lower kick plate, up the driver-side A-pillar and over the headliner.


Remove the stock mirror, replace it with the new monitor mirror and attach the mirror plugs to the camera’s wiring harness.


Route the system’s power leads from the mirror through the headliner and down the A-pillar, where you’ll tie it into the main fuse block. Note the separate leads for the reverse circuit, ignition power and ground.

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