denny the blue wires are hooked to the big bat. wire. + alt. and +ign. hot all the time.

skids72, you're saying thats the same as pulling the neg. cable off of the bat. to see if your alt. is charging, and you might be right there, but why would you want to cut the motor off with the cut off sw. with the motor running and the ign. sw. on? if you're planning on doing that much, then you'll need the dioded. if you cut the "ign. sw. off," then the motor want be turning, so it cant produce elec. so the motor can't run. the only reason i put a cut off sw. in a st. car is to cut the bat. out of the system while its sitting still, with the ign. off. they use them at the drags mostly to cut the fuel pump off, not cut the motor off, and it dont make no dif. where you put the cut off sw. at.