GM Update 661.40: New OTA Software Update Listed for Silverado EV and Sierra EV
GM has a new over-the-air software update listed for the Chevrolet Silverado EV and GMC Sierra EV, and it appears to apply across multiple model years with slightly different release notes depending on the vehicle year.
The update is titled GM Update 661.40 and is listed for both the Silverado EV and Sierra EV. There are two separate source documents: one covering 2024-2025 model year trucks and another covering 2026 model year trucks.
What GM Update 661.40 Appears to Address
For 2024 and 2025 Silverado EV and Sierra EV models, GM lists several improvements and fixes, including:
- Fixes to help ensure successful vehicle software updates
- Fixes to help protect battery life
- Improvements to provide more accurate speed limit detection on the driver’s display
- Improvements to the availability of driver assistance features with fewer notifications or warnings
- Fixes to help ensure driver assistance features remain functional when the windshield freezes
For 2026 Silverado EV and Sierra EV models, the listed release notes are shorter. GM specifically mentions:
- Fixes to help ensure successful vehicle software updates
- Improvements to the availability of driver assistance features with fewer notifications or warnings
Which Components Are Involved?
The documents list several vehicle systems tied to this update. For 2024-2025 trucks, the components include:
- AOS - Automatic Occupant Sensing Module
- FCM - Front Camera Module
- ACP2 - ADAS Compute Platform 2
For 2026 trucks, the listed components include:
- AOS - Automatic Occupant Sensing Module
- ACP2 - ADAS Compute Platform 2
Why This Matters for Silverado EV and Sierra EV Owners
This update looks like one of those behind-the-scenes software releases that may not add flashy new features, but could still matter a lot in daily use.
The big areas to watch are:
- Software update reliability - GM specifically calls out fixes intended to help vehicle software updates complete successfully.
- Driver assistance behavior - The update mentions improved availability of driver assistance features and fewer warnings or notifications.
- Speed limit detection - For 2024-2025 trucks, GM says the update improves speed limit detection accuracy on the driver’s display.
- Battery-life protection - Also specific to the 2024-2025 document, GM references fixes to help protect battery life.
- Cold-weather driver assistance reliability - The 2024-2025 document also mentions a fix related to driver assistance functionality when the windshield freezes.
Is This a Recall?
Based on the documents, this is listed as a GM Over-The-Air software update, not a traditional safety recall notice. The documents reference associated field actions, but the release notes describe software improvements and fixes rather than a stop-drive or urgent safety issue.
That said, owners should still pay attention to software update notifications in the vehicle and the myChevrolet or myGMC app. Some updates may install automatically, while others may require the owner to accept or schedule the installation.
Model Year Differences
The most interesting part is that GM separated the information into two documents. The 2024-2025 model year trucks receive a longer list of noted fixes, while the 2026 model year trucks show a shorter list.
That does not necessarily mean the 2026 trucks are receiving a smaller software package. It may simply mean those trucks already have some of the earlier improvements built in, or that GM is documenting the update differently by model year.
What Owners Should Do
If you own a Silverado EV or Sierra EV, it is worth checking:
- Your vehicle’s software update screen
- The myChevrolet or myGMC app
If you have been seeing frequent driver assistance warnings, update failures, speed limit display issues, or cold-weather camera/ADAS problems, this update may be especially relevant.
As always, software update timing can vary by vehicle, trim, build configuration, and rollout schedule. If your truck has not received the update yet, that does not necessarily mean anything is wrong. GM often rolls these updates out in phases.
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