My interior lights have been coming on by there self at times. It is draining my battery

accessories or a hidden fault.Try disconnecting the ground on your battery now with a short light tester connect between the post and ground cable if the light comes on then pull one fuse at a time to isolate the connection if this is an accessory and the light goes out leave it out.Take note the door open will turn on the interior light and show power drain so hope that helps it's really a job for two.

can i buy a comma? says vanna white?? LOL !
ok, the battery drains, so you got a DRAIN, called phantom drain.
or dark current.!!
we use a thing called an AMMETER (DMM) to find all drains, easy

do you have one, want to learn or just wanting wild guessing.

on any 08 liberty, we check the scan tool data.
oops it shows battery low, wow even the PCM sees that.

new batteries do not fix drain.
nor dead alternators.

get it serviced, by a pro. ?

1: charge battery (rested its 12.6vdc )
2: start engine, scan tool shows, what DTC errors (post em')
3: battery voltage is , 13.3, to 15vdc running, if not charge system is faulting.
4: ok all that is ok, i then key off and measure bettery cable neg lug drain current, if 0.010a to 0.040a its ok, if over 0.1 amps its a drain.
we then find the drain cause, ASK? its not hard with a meter.
but i bet all you wanted is a wild guess.

something to do with the excitation

most come to cause this is intera light charge battery up and check for a drain on the battery with a meter. if this is not the interior light.remove the fuse one at a time and check make sure you know the radio code as you may need to put it back in to get it to work again.,

First step have the battery tested, a bad cell can cause a internal drain and kill the battery, if the batt is ok then check for interior lights like visors that stay on or interior light that come on by themselves at night due to defective door switches.

http://www.2carpros.com/articles/car-battery-dead-overnight
This may help you find the problem.

It sounds like the solenoid that activates the starter is activating, but there isn't enough juice to turn the motor. You say the lights come on, but test it by putting on the interior light, then put on the headlights, if the interior light dims or goes out the battery is almost certainly dead. It might be that you left something on and the battery drained, but sadly, poor batteries will fail completely in cold weather and that's end of life. First step is a jump start from a neighbour. If that starts it, run the vehicle around for half an hour and see if that has recharged the battery. When you come to turn it off to test it, PARK ON A GOOD HILL! Then if the battery is still dead, you can use the hill to roll down and bump start the vehicle (IF ITS A MANUAL OF COURSE). If the jump start fails, If the lights remain on and bright when you test, then you have a starter fault (Probably the starter motor its self). Expect it to be the battery. What you describe is a 90% probability that it is the battery

You possibly have a bad/ shorted door switch. On each doorpost there is a little push in switch that activates the interior lights when the door is opened - if any of these switches short, the lights go on which will drain your battery. You'll need to figure out which switch is messing up and replace that switch. When you open and close your doors, do the lights go on and off respectively? This will take some time to figure out as your car has a delay on the lights to give you time to get the key in the ignition. It is possible that one of the switches has dirty or corroded contacts ( but not very likely ) . This could be a time consuming endeavor and, short of unplugging each door switch, will continue to kill your battery unless you disconnect the battery when parking for long periods ( like at work or overnight).
Hope this helps and please rate my solution!!

I'd remove panel as/if necessary so that I could remove connector at power trunk latch, and see what happens from there. If interior lights work o.k. and no drain, then you found your source of drain/short.

First disconnect the battery overnight just to make sure the battery is not self discharging......if it's dead or down in charge while disconnected....time for a new one.
Now.....if the battery is good....disconnect one battery cable and place a 12 volt test light between the cable and the battery post the cable had just been attached to. A bright light means a drain in the car.
Your job is to remove one fuse at a time until the light dims.
A dim light is OK...clock memory etc.
Remember....a open car door is a drain......the dome light.....so keep them closed while pulling fuses.
Also....if the fuses don't show a drain......disconnect ALL wires from the alternator....there could be a drain there.
Just keep disconnecting one thing at a time until the light goes out or dims.