Test C: The Subwoofer Is Inoperative/Does Not Operate Correctly

PINPOINT TEST C: THE SUBWOOFER IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

Normal Operation
The subwoofer amplifier receives voltage through circuit SBP38 (BN/RD), and ground through circuit GD143 (BK/VT). The subwoofer and subwoofer amplifier are integral to the enclosure, and can not be repaired individually.

To enable the subwoofer amplifier, the audio control module (ACM) sends voltage through the enable/clip circuit SME23 (VT/RD). The circuit acts as both an output (to enable the amplifier) and an input (to detect an amplifier overload condition). A variable resistor in the subwoofer amplifier modifies the voltage signal from the ACM. In the event of an overload, the ACM clips the audio output signal to the amplifier (heard as distortion), in order to prevent damage to the amplifier and speakers.

The clip/enable status is based on the following voltages, as detected by the ACM:
- Less than 0.4 volts: amplifier disabled
- Between 3.8 and 6.7 volts: amplifier enabled
- Greater than 8.5 volts: amplifier clipped

If the clip/enable circuit is shorted to ground, the sound from the subwoofer will be muted. If any of the subwoofer audio circuits are shorted to ground or voltage, distortion will occur.

DTC B1154 (Subwoofer #1 Short to Ground) - sets when a short to ground is detected on circuit SME23 (VT/RD) during the "subwoofer connection test" (part of the ACM on-demand test).

DTC B1155 (Subwoofer #1 Short to Battery) - sets when a short to voltage is detected on circuit SME23 (VT/RD) during the "subwoofer connection test" (part of the ACM on-demand test).

DTC B2913 (Audio Subwoofer Not Connected) - sets when the ACM does not detect the subwoofer through circuit SME23 (VT/RD) during the "subwoofer connection test" (part of the ACM self-test).

This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer
- ACM

C1-C4:

C4-C6:

C6-C8:

C8-C10: