ACM Operation

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

The ACM receives and sends network messages over the HS-CAN3. A diagnostic scan tool can retrieve Diagnostic Trouble Codes (DTCs), PID data and perform other diagnostic functions for the ACM via the vehicle DLC.

The ACM is powered at all times and uses the ignition status message to control the on/off mode. The accessory delay feature is controlled by an ignition status message from the BCM.

The ACM takes various inputs (for example, radio waves, audio signals), conditions and amplifies them, and converts them to an analog audio signal. This signal can be amplified internally and sent directly to speakers, or transmitted to a separate amplifier (for example, DSP) and speaker system.

The BCM ignition status CAN message is used to temporarily mute audio output during engine cranking. This prevents the normal voltage spikes during engine cranking from producing popping noises in the audio system. The ACM receives this message, along with a second duplicate cranking signal via a wired voltage circuit, from the PCM.

The ACM receives vehicle speed information, used to adjust audio volume with different vehicle speeds, from the PCM over the HS-CAN3.