Bulletin No.: PIC6230
Date: Nov-2016

Subject:

Drone Noise At 1900-1950 RPM's

Brand:

Model:

Model Year:
from

Chevrolet

Malibu

2016

VIN:
to

2017

from
All

Engine:

Transmission:

to
All

LFV

All

Involved Region or Country

North America

Additional RPO/s:

NKC

Condition

A customer may comment of a drone/moan type noise that can be present while the vehicle is operating in
the 1900-1950 RPM range.

Cause

This may be due to the ANC (active noise cancellation) system not functioning as intended.

Correction
If the above concern is encountered please perform the following checks and repair as needed.
1.

Verify that the ANC module fuse is good.

2.

Verify that the ANC module connector terminals have proper tension and that the connectors are fully seated.

3.

Play an audio source and verify that each speaker has audio by fading and balancing the output to each speaker individually.

4.

Lower headliner to access the three ANC microphones.
A. Verify terminal tension on ANC Microphone connections.
B. Each Microphone should have 105k-110k OHM's of resistance.
C. The microphone should be centered in the bracket. See the examples below of properly aligned and fitted grill covers.
Note: Shining a white LED light into the grill holes should reveal a centered blue dot. The blue dot is the diaphragm of the microphone and if it is not
centered a realignment of the mic will be required.

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D. The microphone bracket needs to be flush to the Headliner.

2

Gaps are very bad for ANC performance. The adhesive material may need to be removed and the bracket re-bonded to headliner substrate.

After repair using available hot glue. This has a good fit to headliner substrate (no gap).
5.

Verify that there are no mechanical issues causing an unwanted noise/vibration causing the ANC system to incorrectly try to compensate through the
audio system, A/C mounting bracket loose, hoses rubbing on engine compartment, etc.

If these checks are made and no concerns found, then engineering is aware of the concern and is working on a resolution. Connector X3 at the ANC module
can be unplugged and secured until the fix is available. Unplugging the X3 connector will disable the ANC system but allow the rest of the audio system function
as designed. Once the fix is available, the connector can be reinstalled and normal operation should resume.
Note: The correction for this concern may be one of several repairs described above. For vehicles repaired under warranty, please use the appropriate
warranty labor operation based on the actual cause and repair.

Warranty Information
Labor Operation
3480458*

Description
Disconnect the Active Noise Cancelation (ANC) Module

Labor Time
0.2

*This is a unique Labor Operation for Bulletin use only.

Customer Information
Please communicate to the customer that we apologize for this inconvenience and that General Motors is working on a solution for this concern. Once a

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solution is available, this PI will be updated with additional details - allowing dealership personnel to contact the customer to schedule a service appointment and
repair the vehicle.

Version

1

Modified

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may
occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools,
safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that
your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

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