System Overview: Signals

The chart below summarizes the input signals to and output signals from the steering wheel module (SWM). The signal types are divided into directly connected signals, serial communication and Controller area network (CAN) communication. The following illustration displays the same information with the Volvo component designations.

Input signals	Output signals
Via serial communication:	Via serial communication:
Steering wheel buttons, digital signal from the buttons to the steering wheel module (SWM): Cruise control unit (3/4) Audio/carphone switch (3/131) RTI switch (3/135).
Via Controller Area Network (CAN) communication:	Via Controller Area Network (CAN) communication:
Central electronic module (CEM) (4/56).	Engine control module (ECM) (4/46) Transmission control module (TCM) (4/28) Upper electronic module (UEM) (4/70) Accessory electronic module (AEM) (4/78) (optional equipment) Audio module (AUM) 16/1 (optional equipment, not XC90) Central electronic module (CEM) (4/56) Driver information module (DIM) (5/1) Phone module (PHM) (16/60) (optional equipment) Rear electronic module (REM) (4/58) Road traffic information module (RTI) (16/45) (optional equipment, not XC90)

Fig 1: Identifying Steering Wheel Module (SWM) Input/Output Signals

Courtesy of VOLVO CARS OF NORTH AMERICA.