[SwissXC90]

Anything above 10mA to 20mA when car is asleep is too high

You cannot diagnose this stuff with a light bulb

You need to use a multimeter set to Amps.
Be aware that the car uses many amps (A) when the key is on, and only a few milliamps when off (mA). So make sure the multimeter can show a range of (say) 10A down to 0.001 A (1mA)

You need to understand how much time it takes for the car to completely shut down and go to sleep - a few minutes on my 2009 XC90. The CAN busses stay active for a while.


Start with a paper log book. write down the current consumed when car is asleep

Then start the long and painstaking process of pulling one fuse and waiting for the car to go to sleep, and writing down what the consumption is with that fuse pulled.

Start with all the devices that use power when the car is sleeping: alarm, central locking, remote control, on-call system, etc.
Before removing the fuse for the central locking, confirm your physical key still works in the driver's door. You do not want to lock yourself out.

Then move on to devices that should be shut down when the key is off and out (radio, engine, gearbox, etc etc)

A paper log is essential here as after a few hours and days, you will never remember what you have and have not checked.