10-11-12, 11:44 PM
Believe it or not, the alternator and regulator would be the easiest thing to change 
Using the fox headlight loom and splicing the headlight section into the squareye loom would be the best thing to do as you could utilise the relays of the foxeye. You may need to run and extra wire to the fuesd headlight wire in the box under the tank. You should not have to change the switches but maybe modify the plugs in the box under the tank.. I posted the wiring diagrams of the 4 fazers models, the 1997/1998 Fazer 400 and the 1998/1999, 2000/2001 and 2002/2003 Fazer 600s in Downloads » Manuals » Fazer 600 » Fazer 400 and 600 models Wiring digrams. Might be usefull to compare the different versions.
Using the fox headlight loom and splicing the headlight section into the squareye loom would be the best thing to do as you could utilise the relays of the foxeye. You may need to run and extra wire to the fuesd headlight wire in the box under the tank. You should not have to change the switches but maybe modify the plugs in the box under the tank.. I posted the wiring diagrams of the 4 fazers models, the 1997/1998 Fazer 400 and the 1998/1999, 2000/2001 and 2002/2003 Fazer 600s in Downloads » Manuals » Fazer 600 » Fazer 400 and 600 models Wiring digrams. Might be usefull to compare the different versions.