Boom or Moan Sounds from Active Noise Cancelation System

The Active Noise Cancelation (ANC) module filtering function may not be operating properly or the ANC microphone may not be seated correctly in the headliner on some 2016-2018 Malibu models. As a result, a loud boom, moan or phasing sound may be heard from the infotainment system either at a low speed/low RPM or at a high speed/high RPM.

If the boom, moan or phasing sound is noticed, check the ANC microphone for the following:

  • Microphone resistance is 105k to 110k ohms
  • Microphone is mounted flush to the headliner with no gaps. The microphone shown below is not flush with the headliner. (Fig. 3)
  • Microphone is centered in the opening in the headliner (Fig. 4)

Fig. 3

 

Fig. 4

After correcting the positioning of the ANC microphone, if needed, drive the vehicle at a low speed/low RPM — approximately 15–20 mph (24-32 km/h) or 1,100–1,200 RPM — and at a high speed/high RPM — approximately 60-70 mph (97–113 km/h) or 1,900–2,000 RPM — to verify if the sound is still present.

If the boom/moan sound is confirmed at a high speed/high RPM, replace the ANC module.

If the boom/moan sound is confirmed at a low speed/low RPM, disconnect the ANC module X3 connector. Drive the vehicle again at a low speed/low RPM. If the sound is eliminated, leave the X3 connector disconnected and secure it to prevent any rattling.

If disconnecting the X3 connector did not eliminate the sound, refer to Symptoms – Entertainment in the appropriate Service Information for additional diagnostic information.

For additional information and part numbers, refer to Bulletin #18-NA-255.

– Thanks to Calvin Kohring

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2 Comments

  1. Yes, after the ANC microphone has been checked and positioned properly and the RPM verified to be at the lower range set.

  2. Paul Burkett says:

    So, if the low speed sound is eliminated by disconnecting the X3 connector, the permanent fix is to leave it disconnected and secure it to prevent a rattle?

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