What is the function of the car reversing mirror?
The rearview mirror, also known as the rear-view camera, is one of the important safety components of a motor vehicle, used to observe the rear and side conditions while driving and reversing. It was invented by British female race driver Dorothy in 1911. According to its installation position, it is mainly divided into external rearview mirrors, internal rearview mirrors, and lower rearview mirrors.
The mirror surface often adopts a convex design to expand the field of vision and eliminate blind spots. Modern rearview mirrors have developed into intelligent safety devices with multiple functions such as heating, electric folding, and blind spot monitoring. With technological progress, electronic rearview mirrors that replace physical lenses with cameras have emerged.
The rearview mirror, also known as the car rearview mirror, is a safety device on a motor vehicle used to observe the rear and side conditions. According to its installation position, it can be divided into external rearview mirrors, internal rearview mirrors, and lower rearview mirrors; according to the mirror surface type, there are mainly flat mirrors, convex mirrors, double curvature mirrors, and electronic rearview mirrors. The external rearview mirror is usually a convex mirror, with an upright and reduced virtual image, providing a large field of vision and helping to reduce blind spots; the internal rearview mirror is mostly a flat mirror, with a true and undistorted image.
Inside the vehicle, a non-glare rearview mirror is usually installed, consisting of a special mirror, two photodiodes, and an electronic controller. The electronic controller receives the forward and rear light signals sent by the photodiodes. If the light source shines on the interior rearview mirror, if the rear light is stronger than the front light, the electronic controller will output a voltage to the conductive layer. The voltage changes the color of the electrochemical layer on the mirror surface, the higher the voltage, the darker the electrochemical layer color. At this time, even if a strong light shines on the rearview mirror, the reflection from the non-glare interior rearview mirror to the driver's eyes will be dim, not dazzling.
The types of faults in the car rearview mirror (i.e., the rearview camera) are diverse, mainly including: malfunction of the adjustment mechanism, mechanical jamming, electronic system failure, abnormal mirror surface, and abnormal folding function. The following are common faults and their causes, sorted according to the latest information:
Main fault types and causes
Electric adjustment function failure
Fault of the adjustment switch: Oxidation, wear, or jamming of the internal contacts in the switch, resulting in the inability to send instructions.
Power supply line problem: Fuse melting, wire bundle breakage, loose connection, or being bitten by mice, causing power interruption.
Adjustment motor damage: Wear of the carbon brushes in the motor, burnout of the coil, or performance decline in low-temperature environments, resulting in inability to drive the mirror.
Gear set jamming or damage: Plastic gears at the output end of the motor break due to insufficient lubrication, aging, or external impact, causing "no sound but no movement".
Body control module (BCM) failure: Some models are managed by the BCM as a unified system for rearview mirror adjustment. Program errors or hardware failure in the module can cause system failures, often accompanied by other electronic functions such as windows and lights malfunctioning.
Mechanical structure jamming or deformation
Foreign matter jamming: Dust, ice, or foreign matter entering the connection between the mirror body and the base, causing excessive resistance.
Frame or connecting rod deformation: Internal mechanical structure bending due to collision or long-term vibration, causing the mirror to fail to move normally.
Freezing in winter: The mirror surface and the shell freeze together at low temperatures, making it easy to damage the motor when adjusting forcefully.
Mirror-related problems
Unclear vision: Dirt, water stains, peeling of the coating, or fogging on the mirror surface, affecting observation at night or in rainy weather.
Mirror cracking or falling off: Cracking of the mirror due to collision or aging, or loosening of the fixing clips.
Automatic folding function failure
Motor or gear failure: Similar to the adjustment motor, the folding motor is damaged or the gears are worn out, resulting in inability to extend or retract.
Sensor or software failure: Some models rely on sensors to determine the folding state, incorrect software judgment or incorrect matching of modules can cause the function to fail.
Fixed screw loosening: The screw connecting the rearview mirror to the vehicle body is loose, affecting the stability of the folding.
Heating function failure (some models are equipped) The heating wire is broken, the fuse has blown, or the control module is faulty, causing the defrosting and dehumidifying function of the lens to fail.
Troubleshooting suggestions:
Priority check: First, confirm if the fuse has blown, and then check if the adjustment switch responds.
Simple handling: Clear the snow and dirt on the lens, and try disconnecting the negative terminal of the battery to restart the system.
Professional diagnosis: If it involves the motor, wiring, or control module, it is recommended to use a diagnostic tool to read the fault code (such as P0950, U1000), and have it repaired by a professional technician to avoid secondary damage caused by.
Safety reminder： The rearview mirror is a key component for driving safety. Any malfunction should be dealt with promptly. Do not drive with a faulty mirror.
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