Pinpoint Test N: Loud Popping Sound When Cycling The Ignition Switch (Late Build)

Information and Entertainment System

Pinpoint Test N: Loud Popping Sound When Cycling The Ignition Switch (Late Build)

Refer to Wiring Diagrams Set 130, Audio System/Navigation for schematic and connector information. Electrical Diagrams

Normal Operation

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

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- ACM (Audio Front Control Module)

PINPOINT TEST N : LOUD POPPING SOUND WHEN CYCLING THE IGNITION SWITCH (LATE BUILD)

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

N1 CHECK THE START INPUT CIRCUIT VOLTAGE

- Ignition OFF.

- Disconnect: ACM (Audio Front Control Module) C290A.

- Disconnect: Starter Relay.

- Hold the ignition in START.

- Measure the voltage between the ACM (Audio Front Control Module) C290A-15, circuit 50-MD15 (GY/RD), harness side and ground.





Is the voltage greater than 11 volts?

Yes
GO to N4

No
VERIFY the BJB (Battery Junction Box) fuse 7 (20A) is OK. If OK,GO to N2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Electrical Diagrams

N2 CHECK THE START INPUT CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Ignition Switch C250.

- Disconnect: BJB (Battery Junction Box) Inline C213.

- Measure the resistance between the ACM (Audio Front Control Module), harness side and the ignition switch, harness side.

Positive Meter Lead Circuit Negative Meter Lead Circuit C290A-15 50-MD15 (GY/RD) C250-7 50-BB16 (GY/BK)






Is the resistance less than 3 ohms?

Yes
GO to N3.

No
REPAIR the circuit in question. TEST the system for normal operation.

N3 CHECK THE START INPUT CIRCUIT FOR A SHORT TO GROUND

- Measure the resistance between the ACM (Audio Front Control Module), harness side and ground:

Positive Meter Lead Negative Meter Lead Circuit C290A-15 Ground 50-MD15 (GY/RD)






Is the resistance less than 3 ohms?

Yes
GO to N4.

No
REPAIR the circuit in question. TEST the system for normal operation.

N4 CHECK FOR CORRECT ACM (Audio Front Control Module) OPERATION

- Connect: Starter Relay.

- Connect: All Disconnected Connectors.

- Disconnect all the ACM (Audio Front Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all ACM (Audio Front Control Module) connectors and make sure they seat correctly.

- Operate the system and determine if the concern is still present.

Is the concern still present?

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

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.