The right rearview mirror of the car - the function of the electric steering mechanism
The reversing switch in the electric adjustment system of the car's right rearview mirror is essentially a core component of the driving motor. Its function is to automatically switch the direction of the current inside the motor, thereby changing the rotation direction of the motor and ultimately enabling the adjustment of the rearview mirror's lens at different angles up and down, and left and right.
Detailed function breakdown:
Changing the current direction to control the motor's forward and reverse rotation: The internal electric rearview mirror usually has two miniature DC motors, each responsible for the up and down and left and right adjustments of the mirror. The reversing switch cooperates with the brush, automatically switching the current direction in the coil during the motor's rotation, allowing the motor to rotate forward or backward, and thereby causing the mirror to swing in different directions.
Maintaining a consistent driving force in one direction: The reversing switch ensures that the force direction of the armature winding remains consistent when rotating in the magnetic field, allowing the motor to continuously and stably rotate in one direction, rather than stopping after a single rotation.
Directly corresponding to the adjustment action: When you press the interior adjustment button, the current direction changes, the reversing switch follows and switches, and the motor then drives the mirror to move up, down, left, and right. For example, to make the right rearview mirror move upwards, the current passes through a specific path to the motor, and the motor rotates forward, causing the mirror to move upwards; reverse the current, and the mirror moves downwards.
The reversing switch is a mechanical component of a brushed motor. Long-term use may cause wear and tear, which may affect the adjustment accuracy or cause abnormal sounds. If the rearview mirror adjustment fails, a reversing switch failure is a common cause, but it also needs to be combined with the motor, control switch, and wiring for further troubleshooting.
The failure of the right rearview mirror's electric adjustment is mostly caused by problems with the single-sided wiring, motor, or mechanical structure. By following the sequence below, you can save a lot of trouble.
First, distinguish the fault phenomenon before taking action:
No response when pressing the button: It is likely a wiring or switch problem. Focus on checking if the internal wiring harness in the door is broken, if the plug is loose, and if the fuse has blown (if the right rearview mirror fails alone, fuse problems are relatively rare, but they cannot be ruled out).
Can hear the motor "buzzing" but the mirror does not move: It is mostly an internal mechanical problem. The most common issue is that the white screw has slipped out of the rubber sleeve, or the gear is stuck. You can try gently pushing the mirror to the middle position and then try again; if it doesn't work, you need to disassemble and inspect.
Up and down movable, left and right not movable, or vice versa: This indicates that the motor itself may be damaged in one half, or the transmission mechanism of the corresponding direction is stuck, and it is necessary to disassemble the rearview mirror assembly for maintenance.
Quick checks that you can do yourself:
First, check the wiring harness at the door hinge. Many vehicles have internal wires broken due to repeated door opening and closing, especially pay attention to whether there is water corrosion (there are cases where water entered the wiring harness and caused a single-sided failure).
Find the corresponding rearview mirror fuse in the fuse box (usually 10A), visually check if it has blown.
Disconnect the rearview mirror plug, use a multimeter to test if there is 12V power supply; directly connect the motor to the 12V battery for testing (the motor does not move within no more than 3 seconds), and if it does not move, it indicates that it is broken.
Only disconnecting the plug and fuse is safe; disassembling the door interior panel and the mirror itself are recommended to be done at a repair shop to avoid breaking the latch or damaging the wiring harness.
Maintenance suggestions: Single-sided rearview mirror failure is usually caused by motor or wiring problems, and it is not necessary to replace the entire assembly. Take the vehicle to the repair shop and let the technician first inspect and confirm the specific cause, then decide whether to repair the wiring, replace the motor, or replace the assembly, which is more cost-effective than directly following the 4S store's advice to replace the entire assembly. If you cannot determine it yourself, directly go to a professional circuit repair shop or 4S store for maintenance. The cost is generally within a few hundred yuan (the cost of replacing the entire assembly is calculated separately).
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