Answer
Jul 23, 2025 - 05:26 PM
No, the upper (inner) tailgate on the 2021 GMC Sierra 1500 AT4 cannot be locked independently.
Here's how it works:
- The entire tailgate locks electronically using your key fob, door lock switch, or passive keyless entry.
- When the truck locks, both the main and inner tailgate lock together.
- There is no separate lock or locking sequence (like holding the button for 7 seconds) that affects only the upper portion.
The “7-second button hold” you're trying is meant to:
- Disable the inner gate release button, to prevent accidental opening, not to lock it.
- This is called inner gate disable mode, and it’s useful if you haul bikes, cargo, etc., and want to prevent someone from opening the inner flap.
- Press and hold the upper tailgate release button for 7+ seconds.
- The tail lamps will flash twice when disable mode is toggled.
This does not lock the inner gate; it just prevents it from opening with the button.
So, how do you secure your tailgate? Just lock the truck using your fob or door lock. If the truck is locked, both tailgate sections stay locked and cannot be opened, unless someone has access to the fob or key.
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