All the key does is turn something down inside the cylinder hole. Sounds like you are not getting the cylinder all the way in, and it's not turning whatever it's supposed to turn. Shine a flashlight down in the cylinder hole and look for the moving part. According to all of the videos I've watched, you have to remove and re-install the cylinder with the key in the "start" position.
https://youtu.be/d5jQ6uLXt58

 

According to all of the videos I've watched, you have to remove and re-install the cylinder with the key in the "start" position.
https://youtu.be/d5jQ6uLXt58

It has to be in the ACC position. And this is really important - you'll do some damage to the switch if you try to pry it out in another key position. It should come out with very little effort if in the right position - you may have to wiggle the cylinder a bit.

 

Hopefully it wasn't drilled straight through and round out the slot in the ignition switch, but it sounds like that happened. If the slot is drilled round, the drill probably moved it to the start position (clockwise drill bit) and then it came back to the run position (spring return), and now rotating the cylinder doesn't engage with the switch. You should be able to see a flat slot in a shiny metal plate and then the same slot in plastic behind it. If it's rounded out go on amazon and buy the $45 replacement (search on "ACDelco D1462G GM Original Equipment Ignition Lock Housing") and just replace the switch, not the whole lock housing - You can't buy the switch separately. You'll probably have to go through the re-learn process since the new switch will probably have a different resistance value presented to the ECM for the passlock function. This is a copy/paste from the alldata.com tech manual for a 2005:

30-Minute Learn Procedure

Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON, vehicle will not start.
Observe the SECURITY telltale. After approximately 10 minutes , the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds .
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes . The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.
Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password.

 

This is what the switch looks like at the end where the cylinder slides into the slot. Note the position of this slot relative to the body of the switch - this is where it has to be to slide it back in with the key in the ACC position. I took this apart, cleaned it and reassembled it and (knock on wood) I haven't had a passlock "wait 10 minutes" problem since.

 

Thanks everybody for the replies. Won't be able to get back to this for a while but look at the posts again when I do.

I will say that the part that the cylinder engages with looks to be intact and sure seemed to be engaging and turning to the appropriate positions. It clicked into all the right spots.

 

Well a year plus later and I'm trying to get this thing started again. The good news: I discovered that a wiring connector under the dash had come loose and that was the source of the electrical issues. I squeezed it back together, locked it, and viola, It turns over.

....But it still doesn't start. I tried the relearn procedure but I'm not sure I'm having a passlock issue at this point.

• For one thing the security light goes on when I'm in the start position but turns off almost immediately when I release to run. My understanding is if the security system was triggered it would stay on or blink for ~10 minutes.
• It fires sporadically. It's rare but it happens. I don't think this should happen if it were the passlock as the injectors are supposed to be disabled, no?

If anyone could tell me if these things mean stop worrying about the passlock and start looking for other things that would be greatly appreciated. Thanks.

 

It doesnt sound like passlock, I would check spark and fuel.

 

Well mostly good news. The next time I tried it it started, so if there was ever a passlock issue it seems to be gone now.

The bad news is it ran for a minute tops then died. After that it would turn over and "start" but die instantly. There's pressure in the fuel line and I can here the pump turn on.

This all started because the truck wouldn't run, the check engine light was on, someone (not me) read the code and decided it was the camshaft position sensor and replaced that, but by the time that happened the key was lost. So possible if not probable the original problem was never fixed but I don't know exactly what it was doing then. The check engine light is off now.

I was going to try siphoning the gas out of the tank and putting some new stuff in. It is over two years old now. If anyone else has any suggestions I'm listening but this old thread has gotten off track so I'm willing to let it die. At least I know it can run.