Audio Whine Noise from Radio Speakers When Using OnStar (Install Noise Suppression Filter)

This bulletin is being revised to update the circuit descriptions in the correction statement. Please discard Corporate Bulletin Number 07-08-46-002A (Section 08 -- Body & Accessories).

Some customers may comment on an audio whine coming from the radio speakers when using the OnStar® system. The amplitude and frequency of the whine will change with an increase or decrease in engine speed.

This condition may be caused by electrical noise on the OnStar® Vehicle Communication Interface Module (VCIM) battery feed wire being passed to the microphone output pins at the radio.

Technicians are to install a noise suppression filter, P/N 1224205, into the OnStar® battery voltage circuit, a few centimeters (inches) from the VCIM. The filter package has three attached wires - a single yellow wire at one end with a yellow wire and a black wire at the other. Install the single yellow wire side into the battery voltage circuit towards the VCIM. Install the remaining single yellow wire into the battery voltage circuit toward the fuse and the black wire to ground.

Important: The noise suppression filter is polarity sensitive. The filter is designed to be most effective when the end with the capacitor ground is connected towards the source of the electrical noise. Install the filter in this polarity first. If the noise level is still not satisfactory, try disconnecting the capacitor ground. In some cases, if the first installation does not correct the noise, try reversing the filter polarity (removing the filter, turning it end for end and then reinstalling it) and grounding the capacitor lead.

For vehicles repaired under warranty, use: