This is a common problem when re-installing power to the car with a low battery.
The passlock/ passkey has activated. Like earlier stated be sure your terminals are clean and TIGHT. Then set the park brake and turn all power accessories off. If the battery is real low put a charger/ boost on it and walk away for 20 minute's. Then approach the car and start it up and all will work for you. It has to relearn your key.

Passkey/ passkey3 and passkey3+


In this system, the vehicle theft
deterrent functions are provided by
the theft deterrent control module.
There is a transponder embedded in
the head of the key that becomes
energized by the exciter coils in the
ignition lock cylinder when the
ignition switch is turned on. The
energized transponder now transmits
a signal containing a unique value to
the theft deterrent control module. If
the module accepts this value, then
there is an additional communication
that takes place between the module
and the key. If the module and the
key agree, then the module sends the
fuel enable password to the PCM. If
the PCM recognizes the password,
then the vehicle starts and runs
normally.

If any of the communication
between the module and the key is
incorrect or the PCM does not
recognize the password, then the fuel
injectors are disabled.

The ignition key is a normal
looking key with no visible contacts
as in the Passkey or VATS systems.
The transponder is located in the key
head. The transponder value is fixed
and cannot be changed. These keys
are usually identified by the letters
PK3, or PK3+ stamped into the steel
body. A relearn will be necessary if
any of the following have been
replaced: any key, the theft deterrent
control module or the powertrain
control module (PCM).

When the theft control module is
being replaced, the module will learn
the existing keys immediately.

However, the PCM must learn the
new fuel enable password from the
new module. If you are replacing a
PCM with a PCM that has been used
in another vehicle or has been
remanufactured, then a relearn must
be performed in order for the PCM to
learn the fuel enable password. Keep
in mind that when you perform a
relearn on this system, all previously
learned keys will be erased from the
theft deterrent control module’s
memory. Any additional keys may be
relearned immediately after the first
relearn has been performed by
inserting the additional key and
turning the ignition switch to the
“On” position within ten seconds of
removing the previously learned key.
In order to initiate the relearn
process:

1. Insert a master key (black
head) into the ignition switch.

2. Turn to the “On” position
without starting the engine. The
security light should illuminate and
stay on.

3. Wait approximately 10 minutes
or until the security light turns off.

4. Turn off the ignition switch and
wait 5 seconds.

5. Repeat steps 2 through 4 two
more times with the same key.

6. Turn the ignition off. The
vehicle will now learn the key
transponder information on the next
start cycle.

7. Start the vehicle. If vehicle
starts and runs normally, and
security light is off, the relearn is
complete.


If additional keys are to be
relearned:

8. Turn the vehicle off.

9. Insert the next key to be
learned and turn the ignition switch
to the “On” position within 10
seconds of removing the previously
used key.

10. Wait for the security light to
turn off. It should happen quickly.
You may not even notice the light
come on, because it will learn the key
transponder immediately.


11. Repeat steps 8 through 10 for
any additional keys.

 

Okay so I tried cleaning off the terminals still no go but I dont know if theyre tight enough they dont come off but the negative wiggles a little. I need to grab a new bolt I think its just a little shaved. But the contacts are very clean and it looks like it's on there well and good.

I tried going through gears and shoving it back up into park hard but not go...I can see the shifter gear itself and it's going all the way up. I do have the key for the passlock which is what I was reading but when I turn my key on to acc the passlock light turns off right away, it does not stay on for more than a few seconds. So I dont know if this means a relearn is necessary? According to the relearn process the light should stay on. The only light that stays on is the engine light.

I don't have an aftermarket radio it's stock, what does a fuel pump sound like? The only sound I hear under the hood is a clicking. If it's the sound of an engine trying to start, it does not get that far.

It seems like the vehicle thinks its not in park...I dont know why..frustrating I dont understand how just disconnecting a battery can do so much damage.

 

If you can move the terminal it is not tight. I use channel lock pliers to squeeze the terminal and then tighten the bolt as these terminals are not like the old thru bolt type.
If you got someone to help, you can loosen the nut then use a small flat-blade screwdriver to open the terminal a little then push it down on the terminal as far as possible. Then grip the terminal end to squeeze it tight and then tighten the nut.(CAUTION: DO NOT SHORT THE POSITIVE )

Now if you know the battery has ample power, put the gear selector in neutral as it will start in park or neutral. If you hear clicking when the key is turned then there is not enough power in the battery... at this point you need a boost with GOOD cables or a battery charger. Nothing should be broke here, at first it was common for the passlock to hold the key but once the light tested and extinguished you should be good to go , unless the battery is low!

 

Well I never did figure it out. Checked I didn't knock anything loose, checked my grounds, battery was good all fuses were good. Wound up having to take it in even though I cant afford it.....hoping they would be able to find a simple fix (they're a pretty reputable repair shop) but they've had it for a day and half now and all they've managed to tell me is that my bcm isn't talking to the rest of my car. They're calling someone familiar with the type of thing...which I dont like none of them are familiar with it...

They said from what I did everything should be working they mentioned passlock but I already tried that so I know that wasn't the issue...they just said the bcm isn't talking to the rest of my car so idk why that would be. So frustrating now I have to find rides to work while they figure it out...theyre already talking about a new bcm why the hell would i need a new one? Is it possible I fried it? This sucks! Theyre making it sound expensive too it's the programming that's expensive isn't it? Theoretically I could go grab a bcm from a similar car at pick n pull?

 

It could be one of three things...1. Coincidental..2. Possible electrical spike through the system...3. A short to ground...hard to say which it is...when you reconnected the battery, did you hook up the ground or positive first? This can make a difference..ALWAYS connect the positive first, if this is what happened...did you try at anytime try to jump start the car?? If jumped incorrectly, this could cause it...when you dropped your tool, something could have shorted...

 

When I first disconnected I removed negative first, however it made 5-6 connections with the terminal in succession because (first time removing a battery I was nervous... ) so maybe that did it.... then i removed positive finally zip tying them away from everything but maybe the damage had been done. What if the tool i was using to undo the positive battery bolt touched a grounded part of the car could that have done it? There was plenty of metal around. Or what if a part of me that was touching the tool touched something grounded on the car? I dont know. When I was done I connected positive first then negative. I really didnt do that much to my car....I know a new bcm and reprogramming wont be cheap from what I've read....

Maybe it was a bad bcm to begin with? From what I've read the 6th and 7th gen bcms seem to go out and just have problems and general. Just sucks a $25 self repair is turning into a freaking nightmare. Not a good confidence booster for my first work ever on my car even though they said I did put the pressure sending unit on correctly T_T Good thing tax seasons coming up...that could have been for so many other things though

 

I did try to jump it too usually I do the positive terminal by my fusebox (not by my battery) and to a ground bolt the negatives connected to. It was late and they were the short cheap jumpers so I just went battery to battery...still shouldn't have affected anything though I dont think?

 

Sorry to hear of the nightmare, a re-flash should cost 150.00 bucks at the most and this includes all modules. These cars are pretty complicated when it comes to electrical.
First thing the dealer should do is to read and clear all modules and verify there is ample power.
Here is a link to some info I posted you can read the whole thread but posting #37,38,39 are the important ones:
charging problem - Page 2 - LS1TECH

Your bcm controls alot of stuff and to say it is not talking to the car is wrong! If anything is not talking to your car it is the tech as he/she can see everything.

 

This is a common problem on the '06 & '07 models. The wiring is poorly routed and movement/rubbing causes one of the wires to separate from the solenoid. The car gets stuck in park and even after manually releasing the shifter the car won't start. Repairing that wire resolves the problem. I sure hope that shop does further diagnostics before soaking you for a BCM.