Audio System

WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to the Owner Literature for additional details of the audio system.

AM/ FM Radio

The audio unit antenna receives AM/ FM radio waves containing data. The data is sent through the audio unit antenna cable to the ACM.

The radio wave data is converted and sent to the audio DSP module over a unique audio bus cable. The data is converted by the ACM and the audio DSP module into fluctuating AC voltage. The ACM provides the fluctuating AC voltage to the front tweeter speakers and the remaining speakers are provided fluctuating AC voltage by the audio DSP module.

To prevent voltage spikes from producing popping noises through the speakers when the ignition is in the START mode, the ACM receives a voltage signal from the PCM-controlled starting circuit. When the ACM detects the voltage signal from the starting circuit, the audio signal output mutes.

A short to ground or short to voltage in the circuitry to one of the speakers may cause multiple speakers to lose sound due to the built-in overload protection feature of the ACM and the audio DSP module. In this case, a speaker fault DTC sets.

The ACM and the audio DSP module provide fluctuating AC voltage to the speakers. Refer to the following lists to identify the speakers associated with the controlling module.

ACM Powered Speakers

Left front tweeter
Right front tweeter

Audio DSP Module Powered Speakers

Center instrument panel
Left front door
Right front door
Left rear door
Right rear door
Subwoofer

Satellite Radio (if equipped)

The satellite antenna sends data through the satellite radio cable to a splitter (integrated into the cable). The satellite radio data is separated from the GPS data and sent to the satellite radio receiver within the ACM. The metadata is displays on the touchscreen display and the audio data is converted and sent to the speakers in the same manner as the AM/ FM radio.

Accessory Delay Feature

The accessory delay feature is a BCM-controlled function that allows the audio system to be operated for a preset period of time after the ignition is turned off and a front door has not been opened.

Battery Load Shed Feature

The BCM uses the battery current sensor to monitor the battery state of charge. When conditions exist to cause the battery load shed feature to activate, the BCM deactivates the battery saver relay (internal to the BCM) and a message is sent over the CAN to turn off selected systems. This turns the audio system off to save the remaining battery charge. To activate the battery saver relay, start the vehicle.

Chimes

Various vehicle systems send chime requests over the CAN to the IPC. The following are determined as the IPC processes these requests:

Chime characteristics such as tone, tone length, number of repetitions, and time between tones
Chime output volume
Priority of the chime request
Specific speakers (front, rear or all) to sound chime

The IPC sends the processed requests over the CAN to the ACM and the audio DSP module. The ACM and the audio DSP module output the analog chime tones to the appropriate audio system speakers as fluctuating AC voltage.

For specific chime information, Refer to: Warning Chimes - System Operation and Component Description .

Speed Compensated Volume Feature

The ACM compensates for wind and road noise by adjusting the audio system volume based on the vehicle speed provided by the PCM over the CAN and the speed compensated volume setting.

ESE (vehicles equipped with 3.5L GTDI)

The ESE is an audio system feature that enhances certain engine tones typically induced under wide open throttle or heavy part-throttle conditions.

The ESE system uses a DACMC (integrated into the ACM) and the audio system speakers.

The DACMC determines the engine tone to enhance based upon engine rotation speed data, engine torque data, and accelerator pedal position data from the PCM. The data from the PCM is processed and converted to an audio signal, transmitted to the DACMC internal tone generator, and output by the ACM to the front door speakers as fluctuating AC voltage.

When the engine is running and the audio system is in use, the audio DSP module outputs to the front door speakers contains a mixture of the ESE frequency with the audio signals from the ACM.

Steering Wheel Audio Controls

The audio/SYNC steering wheel switch contains a series of resistors. Each steering wheel switch function corresponds with a specific resistance value within the switch.

The SCCM sends 5 volt reference voltages to the audio/SYNC steering wheel switch. When a switch is pressed, the voltage is routed through the corresponding resistor to the return circuit through the clockspring to the SCCM. The SCCM monitors the resultant voltage drop to determine the button pressed on the switch.

The audio/SYNC steering wheel switch inputs are sent as network messages from the SCCM to the ACM to control audio functions.