Service Bulletin

Bulletin No.:

21-NA-117

Date:

May, 2021

TECHNICAL
Subject:
Brand:
Cadillac
Chevrolet

Radio Software Version GB108.2 Update
Model:
CT4
CT5
Corvette

Model Year:

VIN:

from

to

2020

2020

2020

2020

from

to

—

—

Engine:

Transmission:

—

—

Involved Region or Country

North America, Middle East, Israel, Cadillac Korea (South Korea)

Condition

Some customers may comment on software related issues. Continuous improvement
software updates are being released with improvements made in several areas. Refer to
the Most Notable Improvements section below.

Cause

The cause of the condition may be software anomalies.

Correction

A new radio software update, version GB108.2, is being released for vehicles equipped
with Infotainment system RPO IOS or IOT, in addition to providing general robustness
and stability enhancements. This update includes all enhancements from previous
software version releases.
This update can occur remotely through in-vehicle prompts from the radio display.
However, some customers may decline the vehicle update, or the update may be
unsuccessful. Along with the vehicles mentioned above, vehicles in unconnected
markets, and fleet customers may need the dealer to reprogram the radio with the new
software package.

Tip: When determining whether this update will
address a customer concern, it is important to
understand what software is currently in the radio being
diagnosed. Depending on the current radio software
version, this GB108.2 update could resolve different
concerns. Example: If current radio software version is
less than GB106, it addresses all concerns listed in all
three Most Notable Improvements sections. However, if
current radio software version is GB107, then this
GB108.2 update would only address the items listed in
the GB108.2 section.
Important: Improvements will vary by model, build
configuration, system, and sales region. Not all
vehicles have all features.
GB106 Most Notable Improvements
Most notable improvements contained in this release
may include:
– Audio
• Loss of chime may occur when switching from
Run to Propulsion after second chime sounds
• No media audio could occur at startup
• Mute could be inoperative while turn signal is
active

Copyright 2021 General Motors LLC. All Rights Reserved.

– Bluetooth
• Contacts may show unavailable, may only
partially download or sync after changing User
Profiles, or may get stuck at any percentage of
the download
– HMI
• Blank screen could occur when transitioning from
Performance Data Recorder (PDR) to radio Home
screen
• Porch/summary view may display Climate Off
message for a couple of seconds after an ignition
cycle
• Using embedded media app (Ex: iHeart) the
Home screen may still display the previous
Source logo
• Upper status bar may not display connected
Bluetooth device information
• Changing Favorites with steering wheel controls
(SWC) may respond slower than changing them
with on-screen touch input
• When rapidly changing Favorites on radio, the
metadata in the DIC Audio Page may not match
what is shown in the radio audio page or Porch/
summary view display
• My Mode, Engine Sound Settings, and Remote
Mirror Folding descriptions may have text cut off

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May, 2021

• Auto indicator in HVAC popup may not illuminate
to match active Auto status
• During an OTA update the radio may display a
Settings page instead of the Programming screen
• Powertrain mode could show Normal instead
of Tour
• (Non-GMNA) The PDR Auto Recording pop up
may only appear in English
• (Non-GMNA) Errors may occur in displaying the
Korean keyboard
Navigation
• Changing language in an active navigation route
could cause nav app to stop working
• In Porch/summary view the navigation maneuver
or highlighted route might get stuck or be
incorrect for next maneuver
Projection
• Android Auto audio may drop out for
approximately one second
• While in CarPlay and during an OnStar Advisor
call, the driver may not be able to hear the
Advisor if a CarPlay incoming call session is
active
• If Android phone enters full sleep it may not
recover connection for Android Auto
Systems
• Improved RVC rolling count diagnostics
• When changing the Teen Driver PIN, a Retry
popup may appear after entering the new number
the second time
• Radio display may be non-responsive to touch
• Radio may create a parasitic battery drain
• With Performance Data Recorder active, shifting
to Reverse may not transition to rear view camera
• If an OTA Download or Install message is
ignored, subsequent ignition cycles might show
Update Available message without first seeing a
Drive to Park shift event
• OTA Install Update message may not appear if
vehicle was started using Remote Start
• During OTA Installation, if ignition mode
transitions to Accessory, Run, or Propulsion
mode as display Update Successful command is
sent, the radio may instead display Update Failed
even though it was successful
• If the LVDS cable is disconnected (during
technician diagnosis) it may cause the radio
System Server to crash
Voice Recognition (VR)
• Connected phone may not respond to Voice
commands
• Voice Recognition may not respond only when
using Sirius XM (SXM) commands
• Voice Recognition may not respond for an entire
ignition cycle

Bulletin No.: 21-NA-117

GB107 Most Notable Improvements
Most notable improvements contained in this release
may include:
– Audio
• Volume may change unwanted
• Volume may ramp up at startup if the Steering
Wheel Control Vol Up is pressed for 3-4 seconds
during bootup
– HMI
• Attempting to make a phone call through a
connected phone or Android Auto, the system
may attempt to make the call through OnStar
• Instrument cluster Favorites and PTT Menus may
disappear for remainder of drive cycle after
changing Favorites
• The Head Up Display (HUD) may not display
SXM metadata if user switches from AM/FM
Favorite to SXM Favorite
• Radio display may toggle or flicker between PDR
screen, Home screen, and PDR screen with
Status bar
• In rare occurrences where powering moding is
changing quickly and repetitively, there may be a
no audio condition at startup until user enters the
Audio app
• May not be able to make an outgoing call when
selecting a contact from the Recent list
• During an OTA update the user may see the
Settings page instead of the Update status
• After an OTA update the user may see the
Update page instead of the Home page
• Error in translations of Ionizer, Location Based
Auto Lift, PDR Auto Recording, and My Mode
• Incorrect message may be displayed in Valet
mode at startup when PDR is only recording
video, not audio
• (Non-GMNA) HVAC dials and radio display may
show mismatched values
– Projection
• Apple CarPlay could display a blank screen
• When using Apple CarPlay Driver Information
Center (DIC) may display device is unreadable
– Systems
• Improve diagnostic algorithm of U3000 Symptom
Byte 4B to reduce occurrences of a false DTC
• Improve diagnostic algorithm of B1A1F Symptom
Byte 00 to configure DTC enable conditions
• Radio display may go blank when user switches
to rear seat infotainment (RSI) secondary video
input
– Voice Recognition
• Navigation app may not launch when using VR

Bulletin No.: 21-NA-117

May, 2021

GB108.2 Most Notable Improvements
Most notable improvements contained in this release
may include:
– Audio
• Increase chime volume for trunk ajar
– HMI
• Driver Information Center (DIC) may be blank
• Favorites list may not appear in the instrument
cluster during an active navigation route
– Navigation
• Directions sent from the myBrand app may be
lost if vehicle is remote started
– Projection
• Apple music may cut out
• The HUD Audio page may overlay the display
every two seconds for an entire drive cycle when
Android Auto is the source
• The song title may not appear in HUD Audio page
when playing Pandora via Android Auto
– Systems
• In very rare cases OnStar may not go to sleep
when OTA Install fails due to a user turning the
vehicle on during its second OTA Installation
attempt
– Voice Recognition
• Native, or embedded, voice assistant may not
work for an entire drive cycle

Service Procedure
1. Inspect the current radio software version.
Navigate to Settings -> About -> Build Number ->
Information “i” to view and verify the software
version.
• If the build number is less than GB108.2, then
proceed to Step 2.
• If the build number is GB108.2 or greater, then
this bulletin does not apply.
Caution: Before downloading the update files, be sure
the computer is connected to the internet through a
network cable (hardwired). DO NOT DOWNLOAD or
install the files wirelessly. If there is an interruption
during programming, programming failure or control
module damage may occur.

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Note:
•

Ensure the programming tool is equipped with
the latest software and is securely connected to
the data link connector. If there is an
interruption during programming, programming
failure or control module damage may occur.
• Stable battery voltage is critical during
programming. Any fluctuation, spiking, over
voltage or loss of voltage will interrupt
programming. Install a GM Authorized
Programming Support Tool to maintain system
voltage. Refer to www.gmdesolutions.com for
further information. If not available, connect a
fully charged 12V jumper or booster pack
disconnected from the AC voltage supply. DO
NOT connect a battery charger.
• Follow the on-screen prompts regarding ignition
power mode, but ensure that anything that
drains excessive power (exterior lights, HVAC
blower motor, etc) is off.
• Please verify that the radio time and date are
set correctly before inserting USB drive into
vehicle for programming, otherwise an error will
result.
• Clear DTCs after programming is complete.
Clearing powertrain DTCs will set the
Inspection/Maintenance (I/M) system status
indicators to NO.
Caution: Be sure the VIN selected in the drop down
menu (1) is the same as the vehicle connected (2)
before beginning programming.

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Important: Techline Connect and TIS2WEB screens
shown above.
Important: If the same calibration/software warning is
noted on the TLC or SPS Summary screen, select OK
and follow screen instructions. After a successful
programming event, the WCC is located in the Service
Programming System dialogue box of the SPS
Summary screen. No further action is required. Refer to
the Warranty Information section of this bulletin.
Important: When programming a module in GM’s new
Vehicle Intelligence Platform, or VIP, the power mode
(ignition) needs to be off or errors may occur. This
involves the 2020 Chevrolet Corvette, Cadillac CT5 and
CT4, as well as the upcoming full-size Chevrolet, GMC,
Cadillac SUVs and Buick Envision. Serial Data
Message Authentication also needs to have the
ignition off.
Tip: If the radio displays Conditions are not ideal, there
are many reasons this can display but be aware that
stable battery voltage is critical during programming.
Any fluctuation, spiking, over voltage or loss of voltage
will interrupt programming.
2. Install the software update. Refer to A11 Radio:
Programming and Setup in SI.

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Bulletin No.: 21-NA-117

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Note: The screenshots above are an example of
module programming and may not be indicative of the
specific module that is being programmed. Module
selection and VIN information have been blacked out.
Important: To avoid warranty transaction rejections,
you MUST record the warranty claim code provided on
the SPS Warranty Claim Code (WCC) screen shown
above on the job card. Refer to callout 1 above for the
location of the WCC on the SPS screen.
3. Record the SPS Warranty Claim Code on the job
card for warranty transaction submission.

Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
Labor
Operation

Description

Labor Time

2887338*

Radio Reprogramming with
SPS/USB for GB108.2

0.6 hr

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Warranty Claim Code Information Retrieval
If the SPS Warranty Claim Code was not recorded on
the Job Card, the code can be retrieved in the SPS
system as follows:
1. Open TLC/TIS on the computer used to program
the vehicle.
2. Select and start SPS/SPS2.
3. Select Settings.
4. Select the Warranty Claim Code tab.
The VIN, Warranty Claim Code and Date/Time will be
listed on a roster of recent programming events. If the
code is retrievable, dealers should resubmit the
transaction making sure to include the code in the SPS
Warranty Claim Code field.

*This is a unique Labor Operation for bulletin use only.
Important: To avoid warranty transaction rejections,
carefully read and follow the instructions below:
• The Warranty Claim Code must be accurately entered
in the “SPS Warranty Claim Code” field of the
transaction.
• When more than one Warranty Claim Code is
generated for a programming event, it is required to
document all Warranty Claim Codes in the “Correction”
field on the job card. Dealers must also enter one of the
codes in the “SPS Warranty Claim Code” field of the
transaction, otherwise the transaction will reject. It is
best practice to enter the FINAL code provided by
SPS/SPS2.
Version

1

Modified

Released May 17, 2021

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.

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