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2021 Corvette: Service Bulletin: #21-NA-053: Radio Software Version V155 Update - (Jun 3, 2021)

#21-NA-053: Radio Software Version V155 Update - (Jun 3, 2021)

Subject Radio Software Version V155 Update

This bulletin replaces PIC6425 and will replace PIT5791 for the models listed. Discard all previous versions of PIC6425 and PIT5791.



Model Year:









Encore GX



















Silverado 1500

Silverado 2500HD/3500HD



Trailblazer (VIN M)





Sierra 1500

Sierra 2500HD/3500HD


Yukon XL


Involved Region or Country

North America, Europe, Uzbekistan, Russia, Middle East, Israel, Palestine, Chile, Colombia, Ecuador, Paraguay, Peru, Japan, Cadillac Korea (South Korea), GM Korea Company, China, Thailand

Additional Options (RPOs)

Equipped with Infotainment Systems IOS, IOU or IOT


Some customers may comment on software related issues. Continuous improvement software updates are being released with improvements made in several areas. V155 contains over 100 improvements. Refer to V155 Most Notable Improvements section below.


The cause of the condition may be software anomalies.


A new radio software update, version V155, was released to service for vehicles equipped with Infotainment system RPO IOS, IOU 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.

Important: Some technicians are reporting that the radio remains on an older software version after the radio displays the software update completed successfully. It is important to ensure that the technician is inspecting the full information found within Build Number and not other rows of information on the same screen. This requires the user to locate the Build Number, and then select the Information icon (circled lower-case i) to see the full software version file name. In these radios, the build number may begin with a letter other than “V” but this is NOT the software version and is not unique to the software release.

Important: After pressing the information icon, review the full software version file name. In the middle of this long file name you see the V155 (or numerically higher if newer versions were released and installed).

V155 Most Notable Improvements

Important: Improvements will vary by model, build configuration, system, and sales region. Not all vehicles have all features.

Most notable improvements contained in this release may include:


  • When answering or ignoring an incoming call, the incoming call popup will not go away until the radio goes through a sleep cycle
  • Phone battery low message flashes when a phone with low battery is connected via Bluetooth
  • Confirm Bluetooth Pairing screen does not display the Pair and Cancel buttons
  • During an active call, another call comes in the first call is still displayed after selecting “Switch (end current call)” and Phone app cannot be launched after ending the call


  • No audible feedback heard when changing state of the setting for HVAC audible feedback on/off

Energy App

  • Target Charge Level shows Away instead of Home when changing Location Based Charging from Off to On
  • Improve Charging Time display to account for a dual mode cord set
  • (Non-GMNA) Enable GPS signal transmission in Radio to allow Location-based Charging feature in non-connected regions


  • The Weather Channel app does not launch when touching the temperature in the status bar
  • The Sirius XM icon remains active when switching Sources from SXM to Pandora
  • The Air Quality Indicator (AQI) index color changes automatically with AQI value
  • Third party apps may appear in full screen after shifting out of Reverse, removing the top and bottom bars from the display at startup
  • An unnecessary battery icon appears at the bottom of the radio display when entering Hands-free contacts when there is no Bluetooth phone connected
  • Cursor will not focus on the keypad when using the multifunction control in the phone name edit screen
  • The Collision/Detection System Settings should be greyed out while vehicle is in motion

IPC Interface

  • When changing languages, the change does not take effect until a page change or a sleep cycle
  • Unable to switch to handsfree from IPC if ignition is cycled off and on during the call
  • OnStar icon may not appear in Head Up Display (HUD) at times when making an OnStar call
  • OnStar icon may remain active in HUD after an OnStar emergency call was ended
  • Blank pop up in IPC when a call is ended, but shows correctly in HUD
  • Call indicator in IPC does not change when switching between hands-free and handset modes
  • FM display is off-center to the right
  • Enable HD Radio message is truncated
  • Phone interface appears on right side of cluster, should appear on the left side


  • Numbers disappear in Direct Tune if pressing them slowly
  • Audio app displays device Bluetooth is not connected when device was paired by Bluetooth from the device side
  • Audio app may not load intermittently. The app may come up briefly then return to the Home page. Issue is recovered by a radio sleep cycle
  • USB media may not play after having used voice recognition or Bluetooth media. Cycling the USB stick recovers USB media operation
  • Android Auto does not display metadata and buttons are unavailable on the Audio Now Playing screen after switching radio User Profiles
  • When on the Audio Off page, pressing a steering wheel control (SWC) button opens the Audio Menu
  • First Favorite is deleted when any other Favorite is deleted
  • iHeart app displays an additional Seek Back button in Turn-by-Turn (TBT) screen that is not present in the app’s main screen, Audio app, or Porch view


  • SD Card Messages “SD Card Error – Launch Nav on Radio for details.” In IPC and “Once initialized, this Nav SD card can only be used for navigation in this vehicle” in Radio appears every ignition cycle when SD card read write switch is in the read-only position
  • Traffic is not shown on cluster and Porch view
  • Navigation startup animation and tutorial appears when speed is >5km/h and the nav app is launched
  • The Predictive card does not return to normal mode after 15 seconds
  • (Non-GMNA) An incorrect address may appear when searching POIs or EV Charging Stations that is either the old address of the POI or combination of the POI’s old and new address
  • After closing the Destination Detail view, the old route may still be displayed in the navigation main screen
  • Native voice assistant is inoperative for an entire drive cycle
  • The map is automatically zooming approximately every 5 minutes while not in an active route
  • The Highway shield icon may flash on the map
  • The Road Alert triangle is too small
  • The Turn Arrow popup for IPC is missing during a maneuver popup
  • The Street Name and Distance to Turn are displayed in the opposite order on the HUD Navigation page
  • Compass arrow is too close to the speedometer in HUD Navigation page
  • Predictive card Traffic indicator appears incomplete when displayed on 10 inch screen
  • Cannot close the “make your driving experience unique by creating a profile” popup in the Navigation app
  • Items displayed in the highway exit list are different depending on whether there is an active route or no route


  • When using the myBrand app to send a destination to navigation and the vehicle is off, the street number or the complete address may be lost
  • When in any IPC submenu of Navigation, pressing the left SWC button exits out of the Navigation menu completely
  • A navigation popup may remain displayed instead of other alerts when exiting while the popup was displayed
  • Unable to change to other IPC pages if a page change was made during an OnStar call
  • TBT view shows Left seek, Pause, and Right seek buttons with Aux audio source
  • Vehicle Location Blocked popup message is automatically dismissed after approximately 8 seconds
  • OnStar Voice Search screen appears answering an incoming OnStar Advisor call
  • TBT Inactive and Active Route views are too close to, and cut off or overlap, other information in HUD


  • Conference Call and call timer does not display in the Center
  • Phone icon does not display in the left on sport mode
  • OnStar TTY keyboard disappears when vehicle goes into motion during an OnStar SuperCruise call


  • When listening to Spotify SWC Favorites switches won’t change songs, instead opening Sirius XM and change to SXM Favorites
  • Connect USB for wired CarPlay, radio does not launch CarPlay
  • Audio cutout or mutes every 10 seconds when vehicle is new, unsold in demo mode
  • Wireless CarPlay will not automatically connect
  • When switching from another source to wireless CarPlay that was previously operating but not active, the display goes blank
  • PTT button does not work at startup in CarPlay but self-recovers later in the same drive cycle
  • Embedded navigation switches back to CarPlay when using Voice Recognition and trying to select from list of destinations. Switching back to embedded navigation you can then select destination from the list
  • Status bar overlays screen during CarPlay phone call
  • Upper bar of wireless Android Auto disappears
  • Unable to enter the Phone app after an ignition cycle
  • After making the wireless CarPlay connection, it may not reconnect if disconnected on the phone side
  • CarPlay audio pauses if RSI video player was used during CarPlay and then switched to RSI audio player
  • Android Auto session drops out on longs trips


  • Lane change assist customization menu incorrect
  • Display flashes while moving the Air Quality Interface slider bar
  • System page is blank when entering Home > Settings > System
  • Visualization Settings is set to Off by default
  • Driver mode visualization page is blank
  • Description of Engine Sound Settings menu is inaccurate


  • {Vehicle Intelligence Platform (VIP) models only}: During a USB File Transfer radio software update the radio may display a statement that conditions are not ideal and to try again later (this is NOT related to installing any OTA Update, ONLY to USB programming of the radio)
  • After installing Spotify, a banner will appear at the top of the screen requesting user to log in for entire ignition cycle
  • The Clear All button in the Notification page overlaps with the OnStar TBT notification Close button
  • (China) Screen turns black when shifting out of Reverse, into Park, while in Valet mode
  • Screen is black for 60 seconds or longer
  • Valet mode cannot be disabled or unlocked
  • Radio boots up slowly, then resets itself
  • Radio stays active after retained accessory power (RAP) timer has expired
  • Unable to increase or decrease SXM channel in Content Area with the multifunction control
  • SuperCruise audible alert, the phrase “take control” is cut off of the “take control of the vehicle now” audible alert
  • Radio locks up or display is blank in cold ambient temperatures

Sirius XM

  • While listening to sources other than SXM, the radio displays a message: “Sirius XM Connection Unavailable - Please Call OnStar Agent” (It is normal, design intent behavior to display this message when a loss of connectivity exists and the user is attempting to play Sirius XM. The software solution does NOT turn off the message completely, it will ONLY change when the message is displayed.)
  • SXM is on Channel 2 after radio sleep cycle if it was previously on Channel 56
  • Sirius XM no audio, or displays XM Loading, or displays Acquiring Signal at startup until switching to another SXM station
  • Radio displays Tuner Initializing on AM, FM, and/or XM
  • SXM shows blank after cycling ignition off and back on

Translation (Non-GMNA)

  • Valet Mode translation to Brazilian Portuguese is not standard
  • Korean translation - Heat should not have been translated in Climate app
  • Android Auto – Switch Session, Switch Phone was not translated to Korean
  • Incorrect Korean translation of “Target Charge Level – Away”

Voice Recognition

  • Improve Offboard Voice Recognition (OBVR) phone book upload
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