Pinpoint Test E: Poor Quality/Distorted/No Sound From The Luggage Compartment Subwoofer

Information and Entertainment System

Pinpoint Test E: Poor Quality/Distorted/No Sound From The Luggage Compartment Subwoofer

Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

The luggage compartment subwoofers are powered by a separate subwoofer amplifier.

To enable the amplifier, the ACM (Audio Front Control Module) sends voltage through the enable/clip circuit. The circuit acts as both an output (to enable the amplifier) and an input (to detect an overload condition). The voltage sent by the ACM (Audio Front Control Module) passes through a variable resistor in the amplifier, then to ground. As the amplifier reaches maximum output, the resistance in the variable resistor decreases. This decreases the voltage drop, resulting in the ACM (Audio Front Control Module) detecting a higher voltage on the enable/clip circuit. When the voltage reaches the clip threshold, the ACM (Audio Front Control Module) clips the audio output signal to the amplifier (heard as distortion) in order to prevent damage to the amplifier and speakers.

The enable/clip status is based on the following voltages, as detected by the ACM (Audio Front Control Module) :

- Less than 0.4 volt: amplifier disabled

- Between 3.8 and 6.7 volts (nominal): amplifier enabled

- Greater than 8.5 volts: amplifier clipped

An open in the enable/clip circuit causes the speakers powered by that particular amplifier to produce no sound because the enable signal does not reach the audio amplifier. A short to ground or short to voltage can cause severe distortion to be heard in the speakers.

- DTC B1A06:01 (Speaker #6: General Electrical Failure)- can set when any fault is detected in the subwoofer speaker circuit. This DTC can be either continuous or on-demand.

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- Speaker enclosure

- Luggage compartment subwoofer amplifier

- ACM (Audio Front Control Module)

PINPOINT TEST E : POOR QUALITY/DISTORTED/NO SOUND FROM THE LUGGAGE COMPARTMENT SUBWOOFER

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.

E1 CHECK THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER FOR VOLTAGE

- Ignition OFF.

- Disconnect: Luggage Compartment Subwoofer Amplifier C4109.

- Measure the voltage between the luggage compartment subwoofer amplifier C4109-7, circuit SBB20 (GN/RD), harness side and ground.

Is the voltage greater than 10 volts?

Yes
GO to E2.

No
VERIFY the Battery Junction Box (BJB) fuse 20 (30A) 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 [1][2]Diagrams By Number.

E2 CHECK THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER GROUND CIRCUIT FOR CONTINUITY

- Disconnect: Negative Battery Cable.

- Measure the resistance between the luggage compartment subwoofer amplifier C4109-10, circuit GD173 (BK), harness side and ground.

Is the resistance less than 5 ohms?

Yes
GO to E3.

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

E3 CHECK THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR CORRECT VOLTAGE

- Connect: Negative Battery Cable.

- Operate the audio system in radio tuner (AM/FM) mode.

- Measure the voltage between the luggage compartment subwoofer amplifier C4109-1, circuit SME51 (GY/VT), harness side and ground.

Is the voltage between 3.8 and 6.7 volts?

Yes
GO to E6.

No
GO to E4.

E4 CHECK THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: ACM (Audio Front Control Module) C290B.

- Ignition ON.

- Measure the voltage between the ACM (Audio Front Control Module) C290B-8, circuit SME51 (GY/VT), harness side and ground.

Is any voltage present?

Yes
REPAIR the circuit. TEST the system for normal operation.

No
GO to E5.

E5 CHECK THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between the luggage compartment subwoofer amplifier C4109-1, circuit SME51 (GY/VT), harness side and the ACM (Audio Front Control Module) C290B-8, circuit SME51 (GY/VT), harness side and ground.

Is a fluctuating AC voltage present?

Yes
INSTALL a new luggage compartment subwoofer amplifier. REFER to Subwoofer Amplifier - Luggage Compartment . CLEAR any DTCs present. TEST the system for normal operation.

No
GO to E7.

E7 CHECK THE AUDIO SIGNALS TO THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: ACM (Audio Front Control Module) C290B.

- Ignition ON.

- Measure the voltage between the ACM (Audio Front Control Module) C290B-5, circuit VME51 (BN/BU), harness side and ground; and between the ACM (Audio Front Control Module) C290B-6, circuit RME51 (WH/BU), harness side and ground.

Is any voltage present?

Yes
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

No
GO to E8.

E8 CHECK THE AUDIO SIGNALS TO THE LUGGAGE COMPARTMENT SUBWOOFER AMPLIFIER FOR AN OPEN OR SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between the luggage compartment subwoofer amplifier, harness side and the ACM (Audio Front Control Module) , harness side; and between the luggage compartment subwoofer amplifier, harness side and ground as follows:

Positive Meter Lead Negative Meter Lead Circuit C4109-3 C290B-5, then ground VME51 (BN/BU) C4109-4 C290B-6, then ground RME51 (WH/BU)

Is the resistance less than 5 ohms between the luggage compartment subwoofer amplifier and the ACM (Audio Front Control Module) , and greater than 10,000 ohms between the luggage compartment subwoofer amplifier and ground?

Yes
GO to E9.

No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

E9 CHECK FOR CORRECT ACM (Audio Front Control Module) OPERATION

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

- Check for:
- corrosion

- damaged pins

- pushed-out pins

- Connect all the 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.