The acoustic parking aid uses ultrasound – like a bat. The devices emit ultrasonic waves that reflect off objects. Sensors then recognize the returning ultrasonic waves. The more ultrasonic sensors there are at the rear of the vehicle, the more accurate the measurement result will be. This enables the parking aid to recognize the distance to possible objects behind the vehicle.
A control unit processes these signals and transmits acoustic warning tones to a signal transmitter. This can be a small LCD monitor or a purely acoustic signal receiver. This generates a beep as a warning signal – the shorter the intervals between the individual tones, the closer there is an obstacle behind the car.
Wireless parking aid for the license plate
The wireless ultrasonic parking aid for the license plate holder with LCD from Lescars offers two advantages: The sensors are already in a holder for the license plate. The signals from the signal generator are also transmitted wirelessly to the monitor. This makes assembly much easier. You don’t have to drill a hole for each sensor individually. Instead, it just needs an additional opening behind the license plate holder, through which the cables of the sensors can be led into the interior.
Depending on the vehicle, it may still be necessary to drill a hole. Vehicle owners can use existing openings in the body or bumper for laying cables, for example those for the license plate lighting. If this is not enough, there is no getting around drilling. However, this requires advanced manual skills. If you drill a hole in the body for this purpose, it should definitely be treated with rust inhibitors afterwards. It is also advisable to seal the hole with sealing compound after installation so that no water penetrates. If in doubt, we recommend visiting a specialist workshop.
Then you plug the cables into the signal transmitter, which is placed in the trunk. Power is supplied via the reversing lights, to which the signal transmitter is connected with a cable. As soon as the driver engages reverse gear, the sensors in the holder for the license plate receive power.
The signal transmitter then transmits the signals to the small 3-inch LCD by radio at 433.92 MHz. This is stuck to the dashboard, the power supply for the screen is provided by the 12-volt plug in the car. This means that there is no need to lay an additional cable through the interior between the signal transmitter and the monitor in the cockpit. The small screen warns the driver with a beep when approaching an obstacle. In addition, the display shows the distance to the obstacle and the position behind the vehicle.
The parking aids from Park Profi and Step by Step, where the parking sensors are also located in the holder for the license plate, work almost identically. In the case of a parking aid without a license plate holder, a single hole has to be drilled for each sensor – this significantly increases the installation effort, as in the case of the Lescars wireless reversing aid PA-280. The advantage: You can distribute the sensors over the entire width of the bumper, which can provide more precise warning signals. But if you do not have strong manual skills and in-depth knowledge of motor vehicles, you should leave that to the experts in a workshop.
Wired parking aids
Variants of the acoustic parking aid without radio connection are also widespread. To do this, the signal transmitter must lay a cable up to the front of the cockpit, which is then connected to a monitor or loudspeaker for the acoustic warning signals. This increases the work involved in installation, so you don’t have to worry about the radio signal being disturbed. Here, too, car owners make life easier with a solution that already integrates the sensors in the license plate holder, as in the Renkforce model.
An acoustic ultrasonic parking aid does not cost the world. For as little as 50 euros you can get a wireless parking aid with sensors in the license plate holder. These usually offer simple assembly, as they transmit the warning signals by radio to a monitor or loudspeaker in the cockpit. Since the power supply comes from the reversing light, in many cases there is no avoiding drilling a hole. If you don’t have strong manual skills, you should have it done by a professional.
Parking aids without radio connections increase the installation effort, since the signal transmitter has to be connected to a monitor or loudspeaker with a cable. It becomes the most challenging with a solution in which the sensors are individually mounted in the bumper – that means one hole per sensor and even more cables to be laid. Only professionals should really work here.
A further alternative as a parking aid are reversing cameras. These are usually attached to the license plate holder. The camera transmits the image to a separate monitor in the cockpit by radio or cable connection. We show a selection of options for retrofitting in the guide to wireless reversing cameras for retrofitting from 100 euros. Further useful accessories can also be found in our car-themed world.