3.1.9.c Ignition lock or recent trend - button for turning on the ignition and starting/stopping the engine
The key in the lock can be switched to several positions, each of which has a specific purpose. In one position, the power of all auxiliary electrical systems is turned on. That is, electricity is supplied to all consumers - from the audio system to the interior lighting and the operation of window regulators (usually this position is called ACC), and the steering wheel is unlocked. If you turn the key further - to the ON position - the engine ignition system will be switched on and self-diagnosis of all vehicle systems starts (this usually takes 2-4 seconds).
Unlike the ignition lock, the button has no fixed positions. Often, you need to press the button and release it within 1-2 seconds in order to turn on the ignition. Press the button a second time and hold it in order to start the engine until it starts. In premium segment cars it is not necessary to hold down the button to start the engine. It is enough to press it briefly after turning on the ignition.
Some manufacturers, who pay tribute to sports, install a separate ignition switch and a separate engine start button (“hello” from Porsche).
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