I hate that problem, and the south asian rats LOVE to eat german wiring - this problem is faced by many mercedes benz owners in Pakistan - and they would eat something somewhere that you have to dismantle half the car to repair it.
remedy is two part.
one - buy a trap - put some nice lovely food in it.
two - buy some liquid ammonia, and apply it to the chassis crossmember of the car - they dont like the smell of ammonia).
Ive had some weird experiences.
first was a big fat rat in the engine bay who thought that he could stop the A/C compressor belt with its teeth, it was beheaded and made a large mess - YUCK - had to drive back home and take the pressure washer to the engine room.
second were a pair of kittens on a december morning, I sat in the car, put the key to preglow - and heard MEOW (hmm I dont have a cat sound chime) - I opened the bonnet to find two very young kittens sitting on the air cleaner box.