Hey guys sorry if this thread seems unnecessary but I posted in other threads and didn't get an answer. I recently unhooked my battery to put in a new head unit and wen i reconnected the battery my car won't start any more and the security light comes up on the dash. I'm wondering if its just a dead battery but the interior/trunk lights still come on when i open the door/trunk so I'm totally confused, someone please help me out!

 

im pretty sure the security light is because of the new head unit, but i may be wrong. as for the car not starting, maybe you didnt connect the battery correctly?

 

red to red... black to black...... + to +... - to -.... positive to positive.... negitive to negitive.... lol haha j/k

yea idk wy i wouldnt be starting the only thing i can think of is you didnt hook the battery back up the right way.. maybe you reversed it

 

Well dude to be honest it could be a few things I'd start by doing a key relearn which is easy to do w/o any tools ill get the process for you

1. With a master vehicle key, turn ON the ignition, with the engine OFF.
Observe the security indicator. After approximately 10 minutes, the telltale will turn OFF.
2. Turn OFF the ignition, and wait 5 seconds.
3. Repeat steps 1-3 two more times for a total of 3 cycles or 30 minutes.
Important: The vehicle learns the key transponder information and/or passwords on the ignition switch transition from OFF to RUN. You must turn the ignition OFF before attempting to start the vehicle.

4. With a master vehicle key, start the vehicle. The vehicle has now learned the key transponder information and/or the ECM has now learned the fuel continue password.

Make sure your headlights are off otherwise the battery will die. If this does work to learn the new key is easy. Just place the working key in the ignition and starte the vehicle. Very quickly, turn the vehicle off remove the working key, and try to start the vehicle with the key that doesn't work

 

I don't even have the new head unit in any more, I took it out in case that was it, still no go

I'm not that dumb, I only unhooked the negative terminal, and I've rechecked it multiple times for a secure connection and it should be fine.

I'll give this a try and I hope it works cuz the step after (4) obviously won't work since I can't start the car at all! Also, any ideas as to what the hell caused this problem?

just thought of something else - i removed a small metal bracket from behind where the head unit sits in order for the new one to fit better - could this possibly be the cause of the problem?