Pinpoint Test E: Loud Popping Sound When Cycling The Ignition

Information and Entertainment System

Pinpoint Tests

Pinpoint Test E: Loud Popping Sound When Cycling The Ignition

Refer to Wiring Diagram Set 130 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Audio System/Navigation for schematic and connector information. Diagrams By Number

Normal Operation

Voltage is sent from the Smart Junction Box (SJB) to the Audio Control Module (ACM) through the start input circuit when the ignition is in the START position. Upon receiving this signal, the ACM mutes all speaker outputs to eliminate the possibility of voltage spikes producing a popping noise through the speakers.

For the Premium sound system, the ACM disables the subwoofer while the ignition is in the START position by keeping the enable signal below 0.4 volt. If there is a short to voltage on the input circuit, distortion is heard in the subwoofer whenever the ACM is powered up, and that should be the primary concern addressed. If the subwoofer has distorted sound, GO to Pinpoint Test D. Pinpoint Test D: The Subwoofer Is Inoperative/Does Not Operate Correctly

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- Subwoofer (Premium sound)
- ACM




PINPOINT TEST E: LOUD POPPING SOUND WHEN CYCLING THE IGNITION

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

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E1 CHECK THE INPUT CIRCUIT FOR VOLTAGE



- Ignition OFF.
- Disconnect: ACM C240a.
- Disconnect: Starter Relay.
- Hold the key in the START position.
- Measure the voltage between the ACM C240a-15, circuit CBP28 (GY/VT), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
For the Premium sound system, GO to E2.

For all others, INSTALL a new ACM. REFER to Audio Control Module (ACM) Audio Control Module (ACM). TEST the system for normal operation.

No
VERIFY the SJB fuse 28 (5A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation. If not OK, Refer to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number

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E2 ISOLATE THE SUBWOOFER



- Ignition OFF.
- Connect: ACM C240a.
- Disconnect: Subwoofer C466.
- Cycle the key through all of the ignition switch positions.
- Is a loud popping sound present?

Yes
INSTALL a new ACM. REFER to Audio Control Module (ACM) Audio Control Module (ACM). TEST the system for normal operation.

No
INSTALL a new subwoofer. REFER to Speaker - Subwoofer Speaker - Subwoofer. TEST the system for normal operation.

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