Pinpoint Test F: Loud Popping Sound When Cycling The Ignition Switch
Information and Entertainment System
Pinpoint Tests
Pinpoint Test F: Loud Popping Sound When Cycling The Ignition Switch
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number
Normal Operation
Voltage is sent through the start input circuit CBP13 (GY/BN) to the Audio Control Module (ACM) with the key in the START position. Upon receiving this signal, the ACM mutes all speaker outputs to eliminate the possibility of speaker pops during engine cranking.
For the Audiophile audio system, the ACM disables the subwoofer while the key is in the START position by keeping the enable signal below 0.4 volt on circuit SME23 (VT/RD).
For the THX(R) audio system, the ACM disables the audio Digital Signal Processing (DSP) module while the key is in the START position by keeping the enable signal below 0.4 volt on circuit CME27 (YE/VT).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer amplifier (Audiophile)
- Audio DSP module (THX(R) audio system)
- ACM
PINPOINT TEST F: LOUD POPPING SOUND WHEN CYCLING THE IGNITION SWITCH
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
-------------------------------------------------
F1 CHECK CIRCUIT CBP13 (GY/BN) FOR VOLTAGE
- Ignition OFF.
- Disconnect: ACM C290a or C240a.
- Disconnect: Starter Relay.
- Hold the key in the START position.
- Measure the voltage between the ACM C290a-15 or C240a-15, circuit CBP13 (GY/BN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
For the Audiophile audio system, GO to F2.
For the THX(R) audio system, GO to F3.
For all others, GO to F5.
No
VERIFY the Smart Junction Box (SJB) fuse 22 (7.5A) 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.
-------------------------------------------------
F2 ISOLATE THE SUBWOOFER AMPLIFIER
- Ignition OFF.
- Connect: ACM C240a or C290a.
- Connect: Starter Relay.
- Disconnect: Subwoofer Amplifier C466a.
- Cycle the key through all of the ignition switch positions.
- Is a loud popping sound present?
Yes
GO to F5.
No
INSTALL a new subwoofer amplifier. REFER to Subwoofer Amplifier Service and Repair. TEST the system for normal operation.
-------------------------------------------------
F3 ISOLATE THE AUDIO DSP MODULE
- Ignition OFF.
- Connect: ACM C240a or C290a.
- Connect: Starter Relay.
- Disconnect: Audio DSP Module C4326c.
- Cycle the key through all of the ignition switch positions.
- Is a loud popping sound present?
Yes
GO to F5.
No
GO to F4.
-------------------------------------------------
F4 CHECK FOR CORRECT AUDIO DSP MODULE OPERATION
- Ignition OFF.
- Disconnect all the audio DSP module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the audio DSP 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 audio DSP module. REFER to Audio Digital Signal Processing (DSP) Module Audio Digital Signal Processing (DSP) Module. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
-------------------------------------------------
F5 CHECK FOR CORRECT ACM OPERATION
- Ignition OFF.
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the ACM 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. REFER to Audio Control Module (ACM) - Fusion, Milan Audio Control Module (ACM) - Fusion, Milan or Audio Control Module (ACM) - MKZ . 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. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------