I went to start the blazer last night and when I turned the key everything went dead in a blink. I can not get the key out now, the key will not turn back past the run position. The battery was fine, but had to go to work and because the key was left in the on position all night it is now dead. What would of or could have caused everything to go out at once?

 

Do you have the original AC Delco battery? These batteries like to corrode inside behind the positive lug. This can cause the symptoms you describe. I too thought the battery in my old Bravada was good. I could turn the key on and the radio would come on, interior lights on, door chime, etc. Turn it to 'Start' and it would die.

The key being stuck in the on position is different, but not unheard of. I'll have to look up the cause as I do not remember it off the top of my head.

Why would you not have disconnected the battery before leaving for work... It is VERY bad for a common car battery to be drained to nothing, especially if it is older.

 

I let time and weather get the best of me. I was already late for work. Anyway, I am concern the factory installed security system may have malfunctioned and shut everything down. There were no problems prior to it not starting. Just got a clen bill of health from the mechanics last week when in for service and inspection. The battery is a top of the line from Auto Zone,less then a year old.
The only other electrical problem I have experianced with this vechile was/is a short in the 4way flashers.

*Combining posts, please use the EDIT function if no one has replied since your last post, thanks. TBB

When I turned the key it seems that what ever went out was as quick as a blown fuse.

 

When I turned the key it seems that what ever went out was as quick as a blown fuse.

 

Well then the next obvious question would be... Did you check the fuses?

 

I have a 2001 Blazer 4 dr 4wd LT. with 105.000 miles. I went to start it and the same thing happened. No elect power when I turn the key. I call AAA to haul it to the Chev dealer. They hooked up all the diao eqip. and it started the first try. This is about the fifth time this has happened but the first time it did not start after a few tries. They suggested replacing the ign switch first. Then the starter and maybe the battery. They also said it could be in the anti-theft system. Any one else with the same issues or any fixes would be great.

 

I have had three mechanics on it for four days. They have pulled and tested everything (fuses, relays, breakers and anything else they can think of) - no luck unless battery is fully charged. Battery will be completely drained in less then two hours. (Intially the battery checked fine, but that was right after the initial shut down) it later completely discharged. All wiring and connections have been check.

 

Well, there is a drain or crossed wire somewhere. Wiring or module faults take time to diagnose. You can narrow it down by removing all of the fuses and putting them back in individually (ie only one fuse in the fuse block at a time), measuring the amp draw as you do so. Once you isolate the affected circuit, move in from there.

I have seen some faults that needed two circuits active. That is a nightmare to diagnose.

 

Eric, It sounds to me like you need to find a new mechanic. If you have that large of a current draw those are the easiest to find, especially on one of these vehicles that don't have that much stuff on them. But just have the battery checked and make sure the positive battery terminal is not coming out of the battery. The security system WILL NOT stop this truck from cranking, it will only shut down fuel so it will not start. Good luck there, if you were closer to me I would lend a hand, but NC is a little to far for me to drive!!