I was just trying to check if it was a specific age/version of
Ibiza that from personal experience, did/could have an issue with incorrectly coded BCM.
Getting fault codes for every controller read is always a good first move, then taking it from there.
One thing to understand is, while that lead probably is supplying the areas of the car that are causing this issue, you have 2 or sometimes more fuses that are providing power to a controller that is allowing power to get "wasted", first the fuse protecting that controller or controllers, and secondly the fuse or fuses that protect the power outputs that that controller or controllers is outputting power to function/functions. I've dived down the "lets stop this happening" and so "locate the source quickly" - and failed miserably, in my case there were no logged faults any where in that car, just battery that ended up getting drained over a few days of not being used.
One approach that I think is helpful is, is to leave the car with the bonnet open if possible, until the controllers have all gone to sleep, then measure the current being taken from the battery - you need to be smart to be able to do this without ending up wakening up any/all the sleeping controllers. My chosen method is to connect one side of a current meter to body/earth using a croc clip, then connect the other side of the current meter down onto the battery -VE post with a sharp long probe, while holding it down firmly, slacken off the battery earth lead and slip it up and so off the -VE battery post, then check the current flow. Noise or rising/falling current usage will either waken up controllers or stop them going to sleep, that can be caused by trapped wires, chaffed insulation or faulty door locking mechanism(s).
You need to able to find a way to allow all the controllers to go to sleep and stay asleep by isolating devices, good luck!
