Why is there no sound from the car's reversing radar?
4 Answers
As a standard parking assistance system, the reversing radar helps us avoid dangers such as scratches and collisions during parking. The reversing radar emits ultrasonic waves through ultrasonic sensors, which reflect back after hitting obstacles and are received by the ultrasonic sensors. The controller then calculates the distance to the obstacle based on the time between the emission and return of the ultrasonic waves, and finally alerts the driver with a rapid beep from the buzzer. The reasons why the reversing radar may not produce sound include: 1. Obstacle is too low: When the obstacle is too low, the reversing radar may fail to detect its presence. 2. Obstacle is too thin: When encountering slender poles, the reversing radar may also fail to detect the obstacle. 3. Reversing radar switch is off: There is usually a switch on the central control panel inside the car that controls the reversing radar. If it is turned off, the reversing radar will not work. 4. Reversing radar wiring fault: When the wiring of the reversing radar is aged or broken, the reversing radar will not function properly. 5. Reversing radar is damaged: Components such as the reversing radar, controller, or alarm may be damaged.
Last time my reversing radar suddenly went silent, and it took me quite a while to figure out the issue. First, I checked the fuse because unstable current often burns out this little thing. Then I found the radar sensor was covered in mud, a spot easily overlooked during car washes. I even specifically tested the buzzer—the multimeter showed normal voltage but it just wouldn’t make a sound, probably due to the speaker aging and going mute. Oxidized wire connectors can also cause poor contact, so I sanded the plugs with sandpaper to restore them. A reminder to everyone: pay extra attention after rainy days, as water seepage into the wiring can easily cause a short circuit. If you’re not familiar with circuits, don’t try to dismantle it yourself—finding a professional is the safest bet; they can pinpoint the problem in just five minutes.
Last week, my car also had the issue of no warning sound from the radar. Let me share my troubleshooting experience. First, check the settings menu—once I accidentally pressed the steering wheel button and turned the volume all the way down. Next, verify if the reverse lights are functioning properly; if the power circuit is broken, the radar system will stop working. Dirty sensors are a common cause—I wiped all four sensors clean with a wet wipe, and they worked fine again. Another time, I found the control box connector in the trunk was loose, and simply reinserting it fixed the problem. If this happens with a new car, it might be due to the buzzer not being securely connected during production. When washing your car, remember to use a low-pressure water spray on the sensor areas, as high-pressure jets can damage delicate components. It’s also a good idea to clean dust from the sensor gaps with compressed air every quarter.
The reverse radar not making sound is mostly due to a circuit system malfunction. I've encountered situations where the buzzer coil was burnt out—replacing the part is just a matter of a few dozen yuan. Damaged wiring is also quite common, especially frequent opening and closing of the trunk can cause wire harness wear. When the power supply is insufficient, the radar will simply stop working; I've tested that it fails when the voltage drops below 9 volts. The most dangerous time was when the sensor was covered in snow and ice, providing no warning at all—almost hit a wall. Cars with modified audio systems need special attention, as amplifier current interference can block radar signals. It's recommended to install an external display for double safety, allowing you to both see the distance and hear the warning sound. For circuit repairs, avoid using ordinary tape—specialized electrical tape is moisture-proof.
