Won't crank...
 

I have an 03 lb7 non egr. So here is the mystery and I'm hoping someone has had this before. I just got back from a trip pulling my fifth wheel. I started the truck this morning to let it warm up. I shut it off to run back in the house and when I tried to restart it I turned the key and when in the start position there is nothing. The starter doesn't even try to turnover. I have checked all fuses in both the inside fusebox and under the hood as well as all of the relays. They are all good. There are no DTC at all. I took out all of the added computer stuff and the truck computer is completely back to stock. This happened once years ago and I can't remember what the dealer told me it was. I think it was the TCM had gone bad.

Any help is greatly appreciated.

Does the key click through the detents off, accessory, and then start and spring back?

IS there any spring tension to return the key back to accessory when you try and start it?

I had to replace the electronic part of the key switch, it clips underneath the cylinder, inside that switch is a gear which meshes with the key cylinder, when i installed the new switch it tok a couple of tries to match the positions up. So at on point had acessory power but no start and the truck would not shut, maybe the nylon plastic gear wore out and skipped a tooth. good luck!

Will it start in neutral. Possibly a bad posistion indicator!

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well if the key cylinder operation is normal. I Would start with the basics, check battery connections again, check voltages while trying to crank (2 person job) one trying to crank and check for signal voltage at the solinoid. also voltage drops along the way at each connection. like mystery said may be a neutral safety issue, try moving the shifter small movements in park while cranking never know. good luck!