General information about the electrical system (Opel Insignia A)

The vehicle uses a single-wire on-board power supply circuit with the negative terminal of the battery connected to the vehicle ground and an on-board circuit voltage of 12 V.

Power supply to most circuits in the vehicle is controlled by a dedicated component, the body control unit (BCM). The ignition switch is a small current switch with several discrete positions for a particular power mode. The power control unit also activates relays and other power distribution elements when necessary. The BCM determines the current power mode (off, on for additional equipment, fully on, starter on) and transmits this information to other power supplies via the data bus.

The table below shows the parameters of the various power modes depending on the position of the ignition switch:

Ignition switch position	Diet	Ignition off/ignition on/starter on	Power for additional equipment/engine running	Engine running/starter on
Off (Off) Key removed	Bull.	Key removed/additional equipment	Inactive	Inactive
Off (Off) Key inserted	Off.	Key in/off	Inactive	Inactive
Accessory (additional equipment)	Additional equipment	Key removed/additional equipment	Actively	Inactive
Run (the engine is running)	The engine is running	The engine is running	Actively	Actively
Start (crankshaft rotation by starter)	The crankshaft rotates	The crankshaft rotates	Inactive	Actively

Source is on the website OpelBook.ru