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

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

Normal Operation
The subwoofer amplifier receives voltage through circuit 828 (VT/LB) and ground through circuit 1204 (BK/OG).

To enable the subwoofer amplifier, the audio control module (ACM) sends voltage through the enable/clip circuit 173 (DG/VT). 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 speaker.

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

An open in circuit 173 (DG/VT) will cause the subwoofer to produce no sound, because the enable signal will not reach the subwoofer amplifier. A short to ground or short to voltage can cause severe distortion to be heard in the subwoofer.

- DTC B1154 (Subwoofer #1 Short to Ground) - sets when a short to ground is detected on circuit 167 (BN/OG) or 168 (RD/BK).
- DTC B1155 (Subwoofer #1 Short to Battery) - sets when a short to voltage is detected on circuit 167 (BN/OG) or 168 (RD/BK).
- DTC B2913 (Audio Subwoofer Not Connected) - may set when the ACM does not detect the subwoofer through circuit 173 (DG/VT).

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

D1:

D1-D4:

D4-D6:

D6-D8: