I know this is an old post, but figured it might help someone if they run into this problem.
Problem: Tahoe displays “Key Fob Programming Mode”, but won’t go into Active Programming Mode when check mark icon is pressed.
The display flashes and goes straight back to same message.
This is the fix, at least for the 2010 Texas Edition Tahoe I was working on yesterday.
Vehicle off, no key in ignition. Open driver side door, and pull the cover off the driver side of dash panel. Usually a pull tab at bottom.
First check the 2A fuses for continuity. If good, locate the three wire harnesses on the fuse panel. You only need to unplug the harness at top left of panel and the one at bottom left of panel. Pull the lock lever straight out and Left and the harness will pop out. Leave both harnesses unplugged for about 30 seconds. Then push them back into place. Make sure the lock lever is completely down and harness is fully seated.
with all doors closed, turn key to ACC position and navigate to the key fob programming screen using the Info button on dash. The vehicle should go into active programming mode once you press the check mark button. Then on the key fob you’re trying to program, press and hold unlock and lock buttons together until you hear the chime noise. You can program additional condone at a time back to back by holding unlock and lock buttons just like you did with first fob. No need to cycle key.
Turn vehicle off and test each fob.
