04 hummer h2 cranks but wont start right after I shut it off
 

Not sure if this is related to your issue but it may be related.

Found this and I quote:-
"
1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to ON, vehicle will not start.
3. Observe the SECURITY telltale light, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds .
5. 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(TM) Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.
IMPORTANT: The vehicle learns the Passlock(TM) Sensor Data Code and/or password XXXXX the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
6. Start the engine. The vehicle has now learned the Passlock(TM) Sensor Data Code and/or password.
With a scan tool clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles.
"

Have a read, its only something I found so I can't verify.

Have you tried holding the gas pedal to the floor while cranking to put it in 'Clear Flood mode" If it will start then, I would suspect a leaking fuel injector, fuel pressure regulator or some other EFI issue.

Coolant temp sensor
 

I fixed the coolant temp sensor and replaced the wire as well. It was damaged and after I cleared the codes. Oddly I drove, Parked and turned the truck off. Waiting 20 seconds (which is usually when it only cranks) but it started right up. Could this have been a factor in the issue? Mind you I know 0% about cars and I apologize if I sound delusional.

Hard to say if a temperature sensor fault is/was the root cause, but stands a chance (see P0114). Erratic readings or over temperature readings could potentially be responsible.

The DTC's can be very helpful, you say you cleared the codes, do you know what they were?



For example heres a list of some general H2 codes, there will also be some relating to Over-Temperature :

https://cimg7.ibsrv.net/gimg/www.hum...5850dfe061.jpg



It would be good to know what guided you towards the temperature sensor, if you can please let us know.

Well the clip of the connector to the temp sensor broke so I replaced both. All the reader said was coolant temp sensor.