Normal Start (Start With Key) Of Engine

Courtesy of VOLVO CARS CORPORATION

Secondary battery relay (2) is not activated and is in normal position (open).
The secondary battery (1) is not connected.
The battery relay (main battery) (4) is not activated and is in normal position (closed).
The vehicle is powered from the battery (main battery) (6).
The starter motor relays (5) are activated (contacts closed) by the Engine control module (ECM). The starter motor's solenoid switches on and the starter motor starts.
The battery diode (3) does not fulfil any function in this mode.