HIGH FREQUENCY NOISE WITH AUDIO SYSTEM DISPLAY ON
IF YOU CONFIRM
There is a high frequency (17 kHz) noise with the audio system display screen turned ON,
NOTE:
 The 17kHz range may not be audible to some people.
 Noise can be heard with the audio system ON or OFF.
AND
The high frequency noise is not heard with the audio system display screen turned OFF,
AND
Service Comm does not show PM991 applies to the vehicle you are working on.
HINT:
If Service Comm shows PM991 does apply to the vehicle you are working on, perform PM991 and do not apply this bulletin.
ACTION
1. Confirm the current Audio Control Unit software version is 321 or 420.
2. Update the Audio Control Unit software version to 423.
