I have a 2003 vauxhall corsa that lost all power. I've recharged the battery (now 12.5 V) but when I connect the terminals a whirring sound(like a fan) comes from a small box to the front left of the fuse box - this is with no ignition on. I've no idea what this component is but suspect if it's running whilst the ignition is off then it will be constantly draining the battery. Any help please!
This is the ABS hydraulic modulator. Vauxhall state this in a technical service bulletin:
Complaint: Noises during engine start and low speed
In case of customer complaint please inform the customer that the ABS/ESP system starts self check after every engine start and with low speed. This behaviour is documented in the owner manual too. No parts needs to be replaced.
When the battery is replaced, I assume it also does a self test as well. Check the manual.
This is normal, but it should not happen all the time. If it flattens the battery then check it again. Your battery could just be dead.
What you can do is split the wire going into abs box and put on isolator switch so when you go out turn it on then when u stop turn it off. Or if you can split cable and extend so you can put isolator on dash so you can do it all from in the car.