Alternator...4 wire to single wire

[godspede619]

1993 Mercruiser 454 7.4 l. Just dropped in rebuilt motor. Connecting wires and hitting some problems. The alternator that is currently on there is a new single wire unit. The wiring and diagram are for the older unit with the excite and sensor wire. So to be clear I have 4 wires total from the harness. Orange, black, red, and purple.

I have read a few posts and want confirmation before I run the wires. Orange goes to B+. Black to ground. Purple gets tied in to any existing purple pre ignition. And the red gets run back to positive battery. Does this sound right? And can that red wire go back to the starter bolt where all the positive wires are from the perko switch?

 

[Bt Doctur]

Re: Alternator...4 wire to single wire

No , for single wire GM the orange is B+, the black is a case ground ,usually one of those Phillips head bolts
the other 2 are taped and turned back, there not used.

 

[godspede619]

Re: Alternator...4 wire to single wire

Okay. I ask cause I read a tread saying to tie the purple back to a purple. And there are existing wires from the previous owner that had butt connectors on a random purple wire.

 

[Bt Doctur]

Re: Alternator...4 wire to single wire

no, the 2 wires are for excite and sense. the exite is switched 12+ .connecting those 2 together powers up the ign circuit and will lead to a dead battery ,look at 4D-2 in here http://www.boatfix.com/merc/Techbk/96/96HGD4.PDF