Electrical issues no power but horn blows until I open driver door... and brake booster constantly running.. key stuck in ignition and in park just rebuilt the transmission.. had it running (like crap) but started and idled shut it off.. went back next morning dead nothing charged battery tried again and I got horn going off and brake booster but no power anywhere else

 

I advise you find a good mechanic to help you. Reading your post I get the feeling you're not real car savvy or familiar with automotive electronics.

FYI. Not sure what you mean by "and brake booster constantly running.." The engine has to be running for the brake booster to "work". The booster is NOT an electrical device but a mechanical part that works off of the vacuum from a running engine.
Sounds like you think your electrical issue is affecting the booster. It's not.

 

Dead battery set the security off.

 

That's my thought as well. Key stuck in ignition is a telltale. The time that the car sat unused while the transmission work was done, the battery went dead. Cold temperatures may have hastened the discharging.

 

[QUOTE=Herhotride;869612]Ok , i cannot imagine why itd be disconnected, and I can only wonder what problems this would cause in general. Can anyone enlighten me. Im replacing the bad battery today, the one that went bad only had 490 cold cranking amps. Im going to get one with 600cc

 

Recently swapped transmission on my 06 hhr when hooking everything back up i was shorting out everything is good and where it should be cleaned... drains my battery no power to anything but my horn blows the brake booster runs constant and rear wiper went back over it all to double check for anything missed or loose nothing... I have a sensor on my battery cable in back that when I unplug it everything works great when plugged in I have no power what is wrong???

 

I put all 3 of your posts here in this thread. Please keep posts about this issue here. Posting the same thing in multiple forums and multiple threads can lead to confusion.

 

You did something wrong.

That sensor around the negative battery cable controls the alternator. I don't know what it could have to do with "no power".