First thing to check is the battery light wire - i had a similar problem on mine last week which i resolved.

When you turn the iginition on does the battery light come on ? If not this is probably your problem but if it does its probably still worth checking.

The blue wire is the one you need to be looking at - the wire is quite thin and it is a regular problem with S2's and is an essential part of the wiring loop as this wire also activates the windings in the alternator which essentially creates charge.

It is usually a "Push on" connection on the alternator and the wire does perish inside the black connector and even in the blue sheath.

This gets affected by heat from the manifold/exhaust/turbo given how close the alternator is to the exhaust/turbo etc and over a long period of time cause the wire to perish.

Check out a thread i started with some good advice on it.

https://passionford.com/forum/techni...or-wiring.html