SCR Metering Valve Question
 

Hey guys,
Does anyone know if the scr metering valve is on the number four circuit on the engine management fuse block? It's a ten amp fuse. I'm trying to narrow down the cause of the fuse blowing. I have numerous codes coming up. Long story short, I replaced the fuse, unplugged the active tank and started it, fuse blew. I also unplugged the transfer pump and replaced the fuse, started it, fuse blew again.
Thanks

found this...

Thanks for the diagram, if you can bear with me, I'm a little out of my element with complex electronics systems like this!
So if I understand this correctly, if I unplug the post catalytic NOS sensor and replace the fuse, start it, there's my problem. If it still blows the fuse, I might be in trouble.
Can you guys let me know, if I'm reading this correctly... The digital diesel electronics control unit is powered by both the number 4 circuit AND the number 1 circuit (20 amp)??
If the electronics control unit is bad, would it not blow both fuses?
I hate to say "hopefully" the NOS sensor is bad or the metering valve is bad. The sound of the "digital diesel control unit" scares the hell out of me!