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Home >> Lincoln >> 2018 >> MKZ Select, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 620 (Information And Entertainment Systems - THX Audio System) >> Diagnosis And Testing >> Information and Entertainment System >> Pinpoint Tests >> Pinpoint Test AU : A Loud Popping Sound Is Heard When Cycling The Ignition >> Notes

Pinpoint Test AU : A Loud Popping Sound Is Heard When Cycling The Ignition: Notes

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

Diagnostic Overview 

Diagnostics in this article assume a certain skill level and knowledge of Ford-specific diagnostic practices. Refer to Diagnostic Methods in Service Information for information about these practices.

Normal Operation and Fault Conditions 

To prevent voltage spikes from producing popping noises through the speakers when the ignition is in the START position, the BCM provides an ignition status CAN message and also applies voltage on the ACM start signal circuit. When the CAN message and/or voltage is received by the ACM, the audio signal output is muted.

Possible Sources 

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