I've had several Corolloas come in lately all with the same problem. The headlights will not turn off, which causes the battery to go discharge while the car is parked. Fortunately, the fix is simple most of the time. The most common cause for headlights staying on all the time is a faulty headlight switch. Here's the repair procedure on a 2006 Corolla.
The first thing I did was to disconnect the battery and hook up a battery charger to the battery because it was completely dead.
The second step to replacing the headlamp switch is to remove the airbag assembly. Do not try to remove the air bag assembly prior to disconnecting the battery. Remove the two bolts holding the airbag into the steering wheel. Once the bolts are removed, you will be able to pull the airbag straight out. Be careful, because the airbag harness will still need to be unplugged from the airbag.
Use a small pick or pocket screwdriver to disengage the wire harness clips from the airbag assembly, and remove the airbag from the steering wheel. Next, remove the nut holding the steering wheel to the steering column. Once the nut is removed, use white-out or a marker to mark the position of the steering wheel prior to removal.
Next disconnect the wire harness connectors connected to the steering wheel. Use a steering wheel puller to pull off the steering wheel off the steering column. Below is what you'll be looking at once the steering wheel is removed.
Next remove the three phillips scews which hold the plastic steering column shroud in place. It's a two piece cover, and it snaps apart and snaps back together, so you might have to pull a little on it. Here's what you'll be looking once you've got the column cover off.
Next, you will need to remove the clockspring. This is a simple procedure. Just disconnect the two electrical connectors going to it, and disengage the plastic clips that hold the clockspring to the steering column. Make sure not to allow the clockspring to rotate after you've removed it, and also make sure to reinstall it back into the same position once you are reassembling the vehicle.
The final step to getting the old headlight switch out is to disconnect the the wire harness connector to the headlight switch and disengage the plastic clips that hold the switch to the steering column. Once the clips are disengaged, the headlight switch will pull right out.
Installation of the new headlight switch is reverse of disassembly. Just make sure to double check that you don't leave any wire harness connectors unplugged, and make sure to reinstall the steering wheel back into the same position it was before the wheel was removed.
The culprit: faulty headlight switch for 2006 Toyota Corolla