Here we go—NOTE that this is for an 09 LTZ--Perhaps yours is the same--
1. Open the driver’s door, kneel down and locate the Junction Block cover that is mounted on the firewall—just above the brake pedal and slightly left.
2. Pull the cover off. There was a plastic “rivet” right in the middle of the cover on my 09 LTZ. Use a trim tool/a pair of screwdrivers to pull the rivet. It takes some pull!! The trim tool did the trick for me—I was able to reuse the rivet.
3. Reach up and squeeze the cover with one hand—squeeze from the sides to the center to release the clips on the cover. Mine was really loose after I removed the rivet it basically fell off.
4. Check out the two rows of multi wire connectors.
5. Look at the left hand row.
6. Just under the left hand row of multi wire connectors you will find an open area with 8 male posts looking at you.
7. The top row far left hand post is 12V ignition controlled power.
8. The top row far right hand post is a ground.
CHECK THIS INFORMATION WITH A VOLT METER BEFORE PROCEDING!!!
9. Press on with the installation.
I know at least six folks have added a key controlled outlet by using this procedure. Note that you will have to install an in line fuse if you tap this power source.
Hope this helps!!
Bob