What is the principle of the original 4-wire central control motor?
4 Answers
The principle of the original 4-wire central control motor is mainly to drive the starter rotor to rotate through electromagnetic induction. The small gear on the rotor drives the generator flywheel to rotate, thereby driving the crankshaft to turn and start the engine. Definition of motor: Motor is the transliteration of the English word 'motor', meaning electric motor or engine. Its working principle is that the energized coil rotates under force in a magnetic field, driving the starter rotor to rotate. The small gear on the rotor then drives the engine flywheel to rotate. The throttle motor is a component of the car air conditioning system. Function of motor: The motor is mainly used to control car idling, with the purpose of adjusting idle speed according to engine load during idling. The idle stepper motor is installed on the throttle body and is controlled by the engine controller to regulate engine idle speed. When the engine speed deviates from idle, the throttle valve adjusts and controls the amount of air entering the intake manifold, which is mechanically operated by the accelerator pedal cable. The throttle has a bypass air passage that supplies air during engine idling (when the throttle is closed). The pivot of the automatic idle motor extends into the bypass air passage to regulate air flow. The engine controller uses input signals from various sensors to move the pivot of the automatic idle motor in and out of the bypass air passage to adjust the engine idle speed. When the ignition key is turned to the 'on' position, the automatic idle motor starts working. This switch signal is input to the ECU to determine whether the engine is in idle condition. Meanwhile, the motor's current position is fed back to the ECU by the motor position sensor.
I've studied the principle of this four-wire central locking motor, which is essentially the actuator for the door lock. The two thick wires control the motor's forward and reverse rotation - for example, when connected to power normally, the motor drives the latch to engage, and when reverse-connected, it unlocks and pops out. The other two thin wires are connected to microswitches. When the latch moves to its limit position, the switches close or open, sending status signals to the body control module. This design achieves both remote locking/unlocking functionality and real-time feedback of door status. If the indicator light doesn't illuminate after locking, it's usually due to an interrupted feedback signal from the microswitch. Inside the motor, there's also a gear set and a limit mechanism that ensures precise movement of the latch by about 1 millimeter. This feedback-equipped design is far more reliable than older pure actuator motors, significantly reducing the likelihood of false lock-ups.
In daily use, I find the four-wire motor quite reliable. Just press the key to lock the door, and the motor inside the door panel buzzes for half a second. The two power wires act like a power switch with reverse wiring, making the motor shaft rotate left or right to drive the latch. The remaining two signal wires are similar to alarm contacts, sending a signal to the dashboard when the lock is in place. Once after rain, the rear door lock got stuck, and the mechanic said it was due to mud clogging the signal switch, causing a misjudgment. As long as you don’t yank the door handle hard, this thing rarely breaks. Some cars can even connect to a mobile app to display the door status, relying on data transmitted through the signal wires.
To diagnose a four-wire motor failure, focus on three key aspects: checking for 12V voltage fluctuations in the power wires, verifying the continuity of signal wires, and inspecting whether the motor gear is jammed. Last time I encountered an unlocking malfunction, I first used a multimeter to measure voltage fluctuations in the wiring harness. The advantage of the four-wire design is its ability to accurately distinguish between mechanical jamming and circuit faults. Nowadays, new car motors are enclosed in dust covers, while older vehicles require attention to water accumulation in door panels that may corrode connector contacts. When modifying audio systems and removing door panels, avoid forcefully pulling the wiring harness—those thin wires are barely thicker than a strand of hair, and breaking them can disrupt all feedback signals.
