Been fighting with this all night, hopefully someone has some insight. 2001 Blazer. When I shut off the truck and remove the key my headlights, and well essentially every bulb in the vehicle stays on. Blower also stays on, can still control the power mirrors, 4x4 switch "operates" but isn't controlling anything. There are three things I've found to turn it all off, unhook the battery, pull the 50A INT BAT fuse under the hood or pull the blue connector out of the BCM. I've pulled the headlight switch, pulled the steering column connector and no change. Checked all the relays in the box under the hood, all fine. Here's where it gets odd. With the 50A INT BAT fuse pulled if I turn the headlights on with the switch I get nothing, until I hit the hi beams. Turn the hi beams off and the headlights are on. Also once I turn on the truck with the 50A pulled everything inside works like it's supposed to. I'm sure there's more but that's a start. I'm hoping there's a relay somewhere weird I don't know about or something simple and not my BCM. ANY help is massively appreciated.

 

Try unplugging the connector at the ignition switch.
Looks like this, about 3" long:

 

Did that, "steering column connector" no effect.

 

Should I try leaving the multi function connectors plugged in since they're not in your pic? Also forgot to mention before all this happened I found my #2 cigar Ltr and my #15 rdo batt fuses inside blown.

Ha! And the cigar fuse inside turns it all off too. Short somewhere perhaps?

Update: 50A fuse in and cigar fuse pulled, courtesy lights don't come on until a door is closed and then it seems RAP has control of them (good 15 minutes before they turn off( pulled RAP fuse courtesy lights stay on)) and...none of my dash illumination works.

 

Update: Think I've got it all figured out. Pretty sure I jiggled my short loose wherever it was, hoping it doesn't come back. And you were right Cap'n someone did a super sorry job wiring in a new ignition switch. The orange lead was all corroded and the electrical tape it was wrapped in was burnt solid. Rewired the whole mess and everything works as it should now. Thanks for the lead. ��

 

We'll keep our fingers crossed Thanks for posting back.