GMC 2007 Envoy - Manual (Page 434)

Back-Up Lamps
The back-up lamps are located in the rear
bumper. To replace a bulb, do the following:
1. Reach behind the rear bumper and locate the
bulb socket.
2. Turn it counterclockwise to remove from the
lamp assembly.
3. Holding the socket, pull the old bulb to
release it from the socket.
4. Push in a new bulb into the bulb socket until it
clicks.
5. Reinstall the bulb socket into the lamp
assembly and turn it clockwise to secure.
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