I had this same problem so I followed the advice of this thread. I swapped out the ignition switch and when I pulled it out, the new plastic gear as in the same place as the new one, with the ignition off. It worked, however it seems like now I have to turn the key a little extra in order for it to turn over. It never did this before. Was that gear just a little bit off or do I need a new tumbler? It was a Standard brand switch. Thanks in advance for any advice.

 

Oh man all the luck, glad you shared that message my 06 LBZ is doing the same thing,so my strange issue is L'll let my truck sit for a few min go out start my truck it shits BUT I have a check engine light ? I pull the codes NO codes,but clear anyway light goes out but there"s that message again shift,do it all over again let it set ,no message but a check engine light,I'm thinking about the ing switch as well,truck has 44k miles its a baby,any ideas out there please share thanks 2006 2500HD Banks,PPE