SBF-4 and main fusebox 2003 WRX
 

I've got a 2003 WRX and in the main fuse box near the battery it has several large 50amp fuses but in the handbook it doesn't tell you what the hell they are for. Has anyone got details of what they relate to or where I can find out?
It is SBF-4 that had blown, can't work out why.
Thanks,

Andy.

I have sent wiring pdf email,if you need more send email