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

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, inline in the OnStar® battery voltage circuit a few centimeters (inches) from the VCIM. The feed circuit wire is red/white and is located in cavity 15 of connector C1 of the VCIM. Connector C1 is a 16 cavity natural colored connector. The filter package has a yellow and a black wire at one end and a single yellow wire at the opposite end. Install the side with the two wires toward the "INFO" fuse (away from the VCIM), installing the yellow wire in circuit 3240 and the black wire to ground. Then install the single yellow wire end towards the VCIM.

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: