Can anybody explain how car central locking works?
Answers:
Have a look at "how stuff works auto section " all will be revealed.
push button - locks go down, push button again - locks come back up.
Depends on which one and what part of it you mean. Generally, there is an electromechanical actuator attached to the manual side of the lock which pushes/pulls the lever to lock/unlock the door. This is controlled by a ECU unit which decodes signals from your keyfob once it's recognised them as correct, otherwise it ignores them and does nothing. The ECU may also have control to split 'zones' so that the drivers door works first, and then if double pressed, the other door opens. Most keyfobs have more than one button, and each button has a different code so that when pressed, the ECU can distingusish between which lock it wants to open. To protect codes from being scanned and duplicated, locks nowdays have codes that change every so often as the ECU unit either transmits a code back to the fob/key to tell it that its changed or it works on an algorithm (a mathematical equation) to change the codes. In older cars, the actuators that push/pulled the locks where done through a vaccum pump that created a vaccum pushing/pulling a diaphram attached to a lever.
when you use a key on the door it sends an electrical signal to all the other locks and this activates a solenoid
Not sure whether you mean central or remote locking, so here goes. Central locking is where the locks on all doors of the car are linked by electronics, adn all have an actuator/solenoid that triggers the locking mechanism when the master (drivers door) lock is triggered by the key/remote. the remote system merely uses a radio signal to trigger this electronic response from the vehicle, which tends to be controlled by the ECU, as this can process what signal is what (alarm, immobiliser, locks etc)
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