My 08 has been great since buying it 3 months ago till last night.
Went to pick up the kid and turned the truck off. 3 minutes later we were back in the truck and when I turned the key the engine cranked fine but would not start. The key would also stick in the crank position. Let go of the key and it would keep on cranking.
I got out and tried the remote start thinking it might be a bad ignition sw but it still just cranked. It was cold and dark so we got a ride home. Went back today and it fired right up and no sticking key. drove it home and shut it of. Same thing would just crank and the key would stay on the crank position even when I let go of it.
I don't get the connection between "no start" and "sticking key".

I think its time to drop the Cummings into it.

 

I would start with checking the battery connection.

Then second thought would be that battery may be going.

Third, starter is going. Next time it wont start, try taking a hammer and bang on the started housing to see if you can get it to free up and function properly.

 

The tip start feature is why it is still cranking after you let off the key. I'd say there is nothing wrong with the starter, battery, or ignition. I say it is computer related. Maybe try and unhook the battery to reset the computer and see if that helps.

Check engine light ever come on?

 

Thanks, now that I know the cranking is NOT a symptom I can carry on troubleshooting the system.
I have a good scan program on my computer so I will pull up any codes. No check engine light. I will also disconnect the battery and see if a reboot helps.
I have whacked many an old starter in my days but only if they don't turn over. You have to be carfull on these new permanent magnet starters to not hit it hard enough to crack the magnets loose from the housing.
I also design and manufacture electric vehicles so I do know a bit about batteries. ;>)

Still think it's Cummings time.

 

You should still be under warranty, no?

 

I would go with Peoples1234 suggestion. Un-hook the battery and let it sit over night to reset the computer.

 

somewhere moisture is getting in the system, how has the weather been lately

 

Clean out the IAC, and the TPS, and the other sensor in the top with some cleaner...

and check the relay that is for the starter, maybe switch it with the other one that is on the wipers(they are the same size)

 

Yeah, I didn't realize that mine had the tip start ignition until I found it by accident one day. It will crank until it gets a run signal, but I'm sure there is a timeout so it doesn't just crank forever. I love the feature though.

Before I'd be swapping out starter relays (since it obviously cranks) I'd try and determine if you have both fuel and spark during the period when it's not starting for you. If you don't have one of them, then go from there. I'd personally be leaning toward the fuel side of things(since we have a COP setup, and they didn't all go bad at once), so check things like the fuel pump relay, fuel pump, etc...I'm not sure if you can get a fuel pressure gauge anywhere on the rails, if you can, you can at least confirm you have fuel pressure to the rail.

 

what's the tip start feature?