Pinpoint Test G: Poor Quality/Distorted/No Sound From All Speakers
Information and Entertainment System
Pinpoint Test G: Poor Quality/Distorted/No Sound From All Speakers
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. [1][2]Diagrams By Number
Normal Operation - All Vehicles
When the ignition is in the START position, voltage is supplied to the Audio Control Module (ACM) through the START sense circuit. When the ACM (Audio Control Module) receives this voltage, it mutes the speaker output.
Vehicles With Sony(R) Sound or THX(R) Sound
The ACM (Audio Control Module) mutes the speaker output by removing the enable voltage to the audio Digital Signal Processing (DSP) module when the ignition is in the START position to prevent popping in the speakers as a result of voltage spikes during engine cranking. However, if there is a short to voltage on the enable circuit, the ACM (Audio Control Module) continuously mutes the audio output, resulting in no sound from all speakers.
To enable the audio DSP (Digital Signal Processing) module, the ACM (Audio Control Module) sends voltage through the enable circuit. The enable status is based on the following voltage, as detected by the ACM (Audio Control Module) :
- Less than 0.4 volt: amplifier disabled
- Between 3.8 and battery voltage: amplifier enabled
An open in the enable circuit causes the audio system to produce no sound because the enable signal does not reach the audio DSP (Digital Signal Processing) module.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Audio DSP (Digital Signal Processing) module (Sony(R) sound, THX(R) sound)
- ACM (Audio Control Module)
PINPOINT TEST G : POOR QUALITY/DISTORTED/NO SOUND FROM ALL SPEAKERS
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings.
G1 CHECK THE START SENSE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM (Audio Control Module) C240A.
- Ignition ON.
- Measure the voltage between the ACM (Audio Control Module) C240A-15, circuit CBP28 (GY/VT), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
For Sony(R) and THX(R) sound systems, GO to G2.
For all other sound systems, GO to G7.
G2 CHECK THE AUDIO DSP (Digital Signal Processing) MODULE VOLTAGE SUPPLY
- Ignition OFF.
- Disconnect: Audio DSP (Digital Signal Processing) Module C4240A (Sony(R) Sound) or C4235A (THX(R) Sound).
- For Sony(R) sound, measure the voltage between the audio DSP (Digital Signal Processing) module C4240A-5, circuit SBP19 (BU/RD), harness side and ground; and between the audio DSP (Digital Signal Processing) module C4240A-6, circuit SBP19 (BU/RD), harness side and ground.
- For THX(R) sound, measure the voltage between the audio DSP (Digital Signal Processing) module, harness side and ground as follows:
Positive Meter Lead Negative Meter Lead Circuit C4235A-9 Ground SBB20 (GN/RD) C4235A-10 Ground SBB20 (GN/RD) C4235A-11 Ground SBB21 (GY/RD) C4235A-12 Ground SBB21 (GY/RD)
Are the voltages greater than 10 volts?
Yes
GO to G3.
No
VERIFY the Smart Junction Box (SJB) fuse 19 (25A) (Sony(R)), or Battery Junction Box (BJB) fuses 20 (20A) and 21 (20A) (THX(R)) are OK.
If OK, REPAIR the circuit in question. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. [1][2]Diagrams By Number
G3 CHECK THE AUDIO DSP (Digital Signal Processing) MODULE GROUND CIRCUITS FOR CONTINUITY
- Disconnect: Negative Battery Cable.
- For Sony(R) sound, measure the resistance between the audio DSP (Digital Signal Processing) module C4240A-13, circuit GD148 (BK/YE), harness side and ground; and between the audio DSP (Digital Signal Processing) module C4240A-14, circuit GD148 (BK/YE), harness side and ground.
- For THX(R) sound, measure the resistance between the audio DSP (Digital Signal Processing) module, harness side and ground as follows:
Positive Meter Lead Negative Meter Lead Circuit C4235B-22 Ground GD148 (BK/YE) C4235B-23 Ground GD148 (BK/YE) C4235B-24 Ground GD148 (BK/YE)
Are the resistances less than 5 ohms?
Yes
GO to G4.
No
REPAIR the circuit in question. TEST the system for normal operation.
G4 CHECK THE AUDIO DSP (Digital Signal Processing) MODULE ENABLE CIRCUIT FOR CORRECT VOLTAGE
- Connect: Negative Battery Cable.
- Connect: Audio DSP (Digital Signal Processing) Module C4240A (Sony(R) Sound) or C4235A (THX(R) Sound).
- Disconnect: Audio DSP (Digital Signal Processing) Module C4240C (Sony(R) Sound) or C4235C (THX(R) Sound).
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the audio DSP (Digital Signal Processing) module C4240C-3 (Sony(R) sound) or C4235C-3 (THX(R) sound), circuit SME23 (VT/RD), harness side and ground.
Is the voltage between 3.8 and 6.7 volts?
Yes
GO to G8.
No
GO to G5.
G5 CHECK THE AUDIO DSP (Digital Signal Processing) MODULE ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM (Audio Control Module) C240D.
- Ignition ON.
- Measure the voltage between the audio DSP (Digital Signal Processing) module C4240C-3 (Sony(R) sound) or C4235C-3 (THX(R) sound), circuit SME23 (VT/RD), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
GO to G6.
G6 CHECK THE AUDIO DSP (Digital Signal Processing) MODULE ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the audio DSP (Digital Signal Processing) module C4240C-3 (Sony(R) sound) or C4235C-3 (THX(R) sound), circuit SME23 (VT/RD), harness side and the ACM (Audio Control Module) C240D-4, circuit SME23 (VT/RD), harness side; and between the audio C4240C-3 (Sony(R) sound) or C4235C-3 (THX(R) sound), circuit SME23 (VT/RD), harness side and ground.
Is the resistance less than 5 ohms between the audio DSP (Digital Signal Processing) module and the ACM (Audio Control Module) , and greater than 10,000 ohms between the audio DSP (Digital Signal Processing) module and ground?
Yes
GO to G7.
No
REPAIR the circuit. TEST the system for normal operation.
G7 CHECK FOR CORRECT ACM (Audio Control Module) OPERATION
- Ignition OFF.
- Connect: All Disconnected Connectors.
- Disconnect all the ACM (Audio Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM (Audio 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 Control Module). REFER to Audio Control Module (ACM) - Fusion 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.
G8 CHECK FOR CORRECT AUDIO DSP (Digital Signal Processing) MODULE OPERATION
- Ignition OFF.
- Connect: All Disconnected Connectors.
- Disconnect all the audio DSP (Digital Signal Processing) module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the audio DSP (Digital Signal Processing) 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 (Digital Signal Processing) module. REFER to Audio Digital Signal Processing (DSP) Module . 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.