Alternator Wiring on Mercruiser

[Sink or Swim]

Greetings all! I have lurked long enough and thought I would finally post to get everyone's thoughts.

I have an 87 Chris Craft with a 175hp Mercruiser 4.3

I removed the alternator to replace it. I have not bought one to replace it yet. It is the original Mercury 12449. There were 2 wires connected to it, a red and black. The back of the alternator has 2 posts where the red and black lugs connected. There are also 3 wires coming out of the alternator where I think is the regulator...red, purple, and black. The black went to the post where the black lug was connected and the red (sensor?) and purple (excitation?) were unconnected. Someone told me I need to go to a 1-wire but what is the black to connect?

If I figure out how to post a pic, that might help what I am babbling about.

Thanks!

 

[ParallaxBill]

Re: Alternator Wiring on Mercruiser

This is how my one wire alternator hooks up. Black looks to be a ground in mine.

 

[Sink or Swim]

Re: Alternator Wiring on Mercruiser

I finally figured out how to place an attachment. The red and purple were unconnected. The black lug was to the post towards the top and the red lug to the post towards the bottom. There is a black wire out of the piece on the back (regulator?) that connects to the top post. This does not agree with the diagram in the service manual.

 

[Sink or Swim]

Re: Alternator Wiring on Mercruiser

I took my alternator to a shop to have them rebuild. They told me to stand on my head and look for 2 more wires that may have connected to the red and purple. They think they were probably hooked up....just poorly and just pulled loose. I will tackle that this evening and hopefully have this figured out before the weekend so the whole fam damily can hit the lake.

Later