Why does the car's power seat move forward and backward with the ignition key?
2 Answers
This is the automatic seat retraction feature, which is a user-friendly function. The power seat system consists of a bidirectional motor, transmission device, and seat adjuster. When the key is removed, the seat automatically retracts fully backward to facilitate entering and exiting the vehicle. When the key is inserted, the seat moves back to the preset position. When the switch is engaged: The motor's power drives the soft shaft to rotate through gears and drive shafts, which then activates the seat adjuster. When the adjuster reaches the end of its travel range, the soft shaft stops rotating. If the motor continues to operate at this point, its power will be absorbed by the rubber coupling to prevent motor overload damage in case the seat gets stuck. When the switch is disengaged: The return spring separates the solenoid plunger from the claw-shaped connector, returning it to the original position. To prevent motor overload, most permanent magnet motors have built-in fuses.
I've been driving for so many years and this is the only situation I've encountered. It's actually quite common for power seats to move forward and backward when you turn the key on or off. This is mostly the seat memory function at work, known as the comfort entry mode. In some cars, when you turn off the engine and remove the key, the seat automatically moves back to give you space to get out; when you insert the key to start, it moves back to its original position for driving convenience. It might be that you haven't set the memory position correctly, or there's interference with the sensor signals, causing the system to reset sometimes. Check the buttons on the side of the seat and reset the memory position, and it should usually be fine. If it still moves randomly, you'll need to check if the wiring harness connectors are loose or if there's an issue with the control unit. Car manufacturers designed this for convenience, but don't let it affect safety. If there's a problem, don't delay fixing it.
