Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
System overview: Signals
The chart below summarizes the input signals to and output signals from the audio module (AUM). The signal types are divided into directly connected signals and Controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.
| Input signals | Output signals |
| Directly connected: CD changer (16/15). Audio signal (Melbus communication) |
Directly connected: CD changer (16/15). Signals used to control the different functions in the changer (Melbus communication). |
| Road Traffic Information Module (RTI) (16/45). Voice information which is played back through the door mounted speaker on the driver's side (Melbus communication). | Amplifier (16/2) (option). Audio signal which is amplified to the loudspeakers. |
| Antenna (16/9 S60/S80, 16/50 V70/V70XC). AM and FM signals via the antenna amplifier (16/16). | Road Traffic Information Module (RTI) (16/45). Control of the TV function and the background lighting for the screen (Melbus communication). |
| Bumper mounted antenna (16/68). FM signals via the antenna amplifier (16/67). | Loudspeakers . Sound reproduction. |
| Via Controller Area Network (CAN): | Via Controller Area Network (CAN): |
| Brake control module (BCM) / Anti-lock brake system module (ABS) (4/16). Volume adjustment depending on speed. | Central electronic module (CEM) (4/56). Confirms that a diagnostic check has been carried out. |
| Steering wheel module (SWM) (3/130). Remote control via the buttons on the steering wheel. | |
| Central electronic module (CEM) (4/56). Luminance of the display and the background lighting for switches. | |
| Phone Module (PHM) (16/60). Mutes the audio module (AUM) when the carphone is in use. (Market dependent). | |
| Accessory Electronic Module (AEM) (4/78). The audio module (AUM) is muted when the handsfree carphone is in use (accessory) or when back-up gear is selected if the car has the back-up warning system (accessory). |
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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.
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