My door ajar light is always on on my 2002 WRX Wagon, I'm 99% sure its the rear hatch that's causing the problem, but i cannot for the life of me find the sensor that determines whether or not the door is open. I expected it to look similar to the ones on the other doors but I can't find anything other than the lock actuator. If anyone knows where the sensor is located it would help a lot in diagnosing my issue, thanks.

The sensor is attached to the housing that contains the latch. You have to access it by pulling off the trim and then there are access holes that you can get to the actuator. Look up part number 63100FE000.

But before going down that route I would determine if it isn't the door sensors. They most definitely wear out and are only like $25 iirc. I have gotten a bit more life out of them by sticking double sided adhesive tape on the sensor or where it contacts the door to compress it a bit more.

thanks for the info, I haven't properly checked to make sure it wasn't any of the other doors, just assumed it was the back since that's the only one that I couldn't find the sensor for.

So guys I've found my problem I hope it works for you guys so first thing I did was test the switch it was good my wires I checked they didn't have power!!! So i noticed that if i pushed on my door really hard form the inside it would cut off the light!!! I thought it was a wire in my door i replaced the whole wiring harness myself it did nothing!!! I then noticed my knee was resting up against my center console when i pushed hard on the center console it went away!!!! Ok so then i pull out my radio it was then it started to act normal idk where exactly but i taped all extra audio and video cable ends with electrical tape maybe they grounded something out maybe it was some wire crimped in there im not to sure i did however put everything back in a uncramped manner and abrakadabra my door ajar is fixed its something that is behind the radio for sure if you guys figure it out please let me know for know mine is back in action!!!