New Alternator-Wiring Question

UNSUREBOATGUY

Petty Officer 2nd Class
Joined
Sep 14, 2009
Messages
117
1987 Mercruiser 3.0 Alpha 1

Just picked up a new alternator for the boat. Its a Sierra 18-5951 3 wire alternator. My question has to do with how to wire it up to the engine. The Orange and black wires are self explainatory, but which wires do I hook up to the red/purple and purple wires coming from the engine harness? The alternator has a black wire and a red wire.

Do I assume that the red wire is colored correctly and that the black wire on the new alternator would have been white on the original? (I never saw the original-I'm replacing an automotive alternator, and I have my doubts whether it was hooked up properly.)

I looked at the manual, but it is still unclear to me. Maybe I just looked in the wrong spot. I looked at section 4C in Manual #10.

Thanks a bunch!
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: New Alternator-Wiring Question

You aren't going to find it in the manual, because Mercruiser never used that type alternator.

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Gamecock1

Cadet
Joined
May 21, 2012
Messages
20
Re: New Alternator-Wiring Question

Im having the same problem. So does the purple and red go to the red and the purple to the black??
 

Gamecock1

Cadet
Joined
May 21, 2012
Messages
20
Re: New Alternator-Wiring Question

Same engine, same alternator, same year, same question. I wasnt aware i needed to start a new thread sorry. It looks to me the red and purple coming from the engin harness goes to the red wire and the purple wire goes to the black wire. Just was looking for some confirmation.
 
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