satnav dvd player or cd changer, mine was switching itself on for no reason

You can buy an "Amp-Hound" test meter on Amazon or you can get this circuit amp draw meter at Harbor Freight for a lot less.

https://www.harborfreight.com/30-amp...xoCemMQAvD_BwE

Here's a video on how to test the circuit with an Amp Meter.
https://www.youtube.com/watch?v=UEYGmSn01Bw

I've noticed the battery voltage dropping abnormally lately. Walked past the X 8n the garage and noticed the light was on by the shifter which it was not doing before so it is not going to sleep properly. I dont have any radio, navi or amp connected anymore. What else can be keeping it awake?

Usually the FSU.

FSU as in blower motor resistor?

Do you have a TCU? Bluetooth. They are known to sometimes not go to sleep.

My 02 does not have a TCU or factory Bluetooth.

That leaves the FSU as the likely culprit as Andrew suggested.

Battery Drain?
 

Haven't seen a blower resistor since the 80s but the 21st century equivalent yep. FSU stands for final stage unit. It controls the power to the blower.

It gets power all the time so when it fails it can pull power always. More often than not, it will still function ok it just never shuts off.

Whuch fuse powers the FSU so I can pull it while its in the garage and see if it goes to sleep?