Central Electronic Module (CEM) (2005-2009): Function: Horn

Fig 1: Horn Communication Diagram

Courtesy of VOLVO CARS OF NORTH AMERICA.

The horn is operated when the steering wheel module (SWM) (3/254) receives a signal from the switches (3/37) in the steering wheel. The steering wheel module (SWM) sends data to the central electronic module (CEM) (4/56) via serial communication indicating that the switch is closed. The central electronic module (CEM) activates the relay for power supply to the horn.

There is also a signal directly connected from the steering wheel module (SWM) to the central electronic module (CEM). This is a Limp-Home function.