The core function of the exterior rearview mirror assembly of a car
The exterior rearview mirror is a key component for ensuring driving safety and can be regarded as the driver's "third eye". Its main functions are as follows:
Expanding the field of vision and eliminating blind spots
When the driver is seated in the car, the direct field of vision is limited. The external rearview mirror can help the driver indirectly obtain external information from the sides and rear of the vehicle, greatly expanding the field of vision. Traditional flat mirror external rearview mirrors can provide images in proportion to the actual object, helping the driver accurately judge the distance of the vehicles behind; while convex mirror external rearview mirrors use the principle of spherical reflection to cover a larger angle of the rear side, effectively reducing visual blind spots. For example, the external rearview mirrors of the Toyota Highlander adopt a double curvature design. The outer large curvature area covers a 60° range of the rear side, and the inner small curvature area is close to the flat mirror imaging, balancing the field of vision and distance judgment accuracy, allowing the driver to promptly detect vehicles, pedestrians, etc. on the rear side and make driving decisions in advance.
Assisting driving operations
In driving operations such as changing lanes, turning, and reversing, the external rearview mirror plays an indispensable role. When changing lanes, the driver uses the external rearview mirror to observe the speed and distance of the vehicles behind, judging whether the conditions for safe lane change are met; when turning, the external rearview mirror helps the driver notice if there are pedestrians, non-motor vehicles, or other vehicles approaching on the side, thus avoiding collision accidents; when reversing, the external rearview mirror allows the driver to clearly see the obstacles on the rear side of the vehicle, combined with the reversing image system, significantly improving the safety and convenience of reversing. Some models also have a rearview mirror that can be lowered when in reverse gear, automatically lowering to a certain angle to display the distance between the rear wheels and the shoulder, further reducing the risk of scraping during reversing.
Enhancing driving safety
Some auxiliary functions of the external rearview mirror also add to driving safety. For example, the heating and deicing function, with nickel-chromium alloy electric heating wires embedded on the back of the mirror, can quickly heat up when powered on, melting ice or evaporating fog, ensuring that the driver can clearly observe the rear road conditions in bad weather such as rain, snow, and fog; the blind spot monitoring function, with millimeter-wave radar integrated in the external rearview mirror, scans the side rear area in real time. When the vehicle enters the dangerous distance, the mirror surface warning light flashes, combined with the steering wheel vibration reminder, effectively avoiding traffic accidents caused by blind spots.
Common faults and solutions of exterior rearview mirrors
Shaking of the rearview mirror
Shaking of the rearview mirror is a relatively common fault, mainly in two situations. One is that the mirror shakes but the shell does not shake, mostly caused by a loose mirror clamp. The solution is to remove the mirror and reinstall it; if the problem persists, it is necessary to replace the mirror. The other is that the shell shakes along with it, possibly caused by loose screws at the connection point between the rearview mirror and the base. At this time, the screws can be tightened; if the problem still persists, it is necessary to replace the rearview mirror assembly at the car repair shop. In addition, excessive wind resistance at high speeds, bumpy roads, and loose internal parts due to vibration can also cause shaking of the rearview mirror. This can be alleviated by replacing the rearview mirror with a more aerodynamic one or improving the vehicle's shock absorption system.
Unable to open the rearview mirror
The reasons for the inability to open the rearview mirror are complex and involve multiple aspects such as mechanics and circuits. Mechanically, it may be that an object has blocked the folding mechanism of the rearview mirror, and clearing the object can solve the problem; it may also be that the gears are worn or the rotating shaft is rusty, causing mechanical jamming, which requires cleaning and lubrication of the mechanical structure, and in severe cases, replacing the damaged gears or rotating shaft. Electrically, a blown fuse is a common cause, and replacing the corresponding specification fuse can solve the problem; aging wiring, poor contact, or motor failure can also cause the rearview mirror to fail to open, requiring checking the wiring connection, repairing or replacing the damaged wiring and motor. Additionally, in the cold winter environment, the lubricating oil at the rearview mirror's pivot point may solidify or ice may form between the mirror shell and the base, causing the rearview mirror to fail to rotate properly. This issue can be resolved by preheating the vehicle and manually cleaning the icy areas.
Rearview mirror adjustment failure
Rearview mirror adjustment failure is divided into unilateral failure and bilateral failure. If a single rearview mirror cannot move, it is usually caused by damage to the unilateral motor, circuit faults, or switch problems. You can first check if the control switch is normal, and then investigate the connection of the circuit. If the motor is damaged, it needs to be replaced. If both rearview mirrors cannot move, it may be caused by faults in the control module, power supply, or main switch. You need to check if the power supply is normal, test and repair the control module, and replace the control module if necessary.
Heating and defogging function failure
Heating and defogging function failure mainly manifests as the inability to heat the mirror or poor heating effect. This may be caused by short circuits, open circuits in the heating element, or aging components. You can use a multimeter to detect the resistance value of the heating element to determine if the circuit is normal. If the circuit is damaged, repair it. If the heating element is aged, replace it. It may also be caused by faults in the control switch or relay. Check the switch and relay, and replace the damaged components.
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