LaCrosse's body computer is located on the dashboard on the driver's side. The body computer is a special microcomputer controller for automobiles. Like ordinary computers, it consists of microprocessor (CPU), memory (ROM, RAM), input/output interface (I/O), analog-to-digital converter (A/D) and large-scale integrated circuits such as shaping and driving. To describe it in a simple sentence is "ECU is the brain of a car".

The main function is to control the start of the vehicle and the opening and closing of the door, glass and door lock, receive and feed back information, and connect the power modules such as engine and gearbox with the switch computer, which means a link between the preceding and the following.