Hello everyone,
Last period of time( mostly in very cold weather) I have problem with my truck to start it. It's not a battery or starter. When you insert the key and turn on ignition to ON position, so all lights are on as usual. But when you try to start truck so nothing happened. it doesn't turn like you didn't turn the key. So this problem persist not every time and sometimes it's working normally. One time I called CAA and when towing truck driver came so he moved shifter from Park to Neutral and other positions for several times. After that he managed to start truck. So right now I am doing the same. When I cannot start truck, so I change gears with shifter sometimes twenty times and after that I can start Hummer. I brought it to mechanic and that time truck started every time, so mechanic couldn't find out what is this. He said it could be security shifter lock.
Any suggestions, what it could be?
Thank you very much!

 

Not 100% sure, but you may want to research "Neutral Safety Switch". Typical GM failure.

 

Thank you very much for your help!

 

Check the shift cable bushing.