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

Input signals	Output signals
Directly connected:	Directly connected: (power supply unless otherwise stated)
Microphone, handset (16/62) Carphone aerial (16/64). Aerial signal, GPS (16/63) (Volvo On Call Plus) SRS signal, GPS (4/9) (Volvo On Call Plus) Handsfree microphone (16/77).	Loudspeaker, handset (16/62) Handsfree speaker (16/78) Carphone aerial (16/64).
Via Controller Area Network (CAN) communication:	Via Controller Area Network (CAN) communication:
Central electronic module (CEM) (4/56) Engine control module (ECM) (4/46) Supplemental Restraint System Module (SRS) (4/9) Driver's door module (DDM) (3/126) Passenger door module (PDM) (3/127) Steering wheel module (SWM) (3/130) Brake control module (BCM) (4/16) Upper electronic module (UEM) (4/70) Driver information module (DIM) (5/1) Road Traffic Information Module (RTI) (16/45) Rear electronic module (REM) (4/58).	Central electronic module (CEM) (4/56) Upper electronic module (UEM) (4/70) Driver information module (DIM) (5/1) Audio module (AUM) (16/1).

Fig 1: Identifying Phone Module Input And Output Signals

Courtesy of VOLVO CARS OF NORTH AMERICA.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

System overview: Signals

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When to See a Mechanic

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