How Do I identify my alternator?

[m7e4d]

Hello all,

I hope I am posting in the correct thread. I have a mercruiser 470 that was without an alternator and had only a broken charging system that I am in the process of replacing. I purchased my brackets to mount an alternator, alternator, and belt from ebay. The brackets and alternator fit together perfectly in the mount and the belt lines up quite well. I am all happy with that. However, I am quite new to working on engines and my alternator appears to have no markings on it other than a sticker that generically says (to the effect) "this meets all necessary guidelines and safety protocols". The regulator on the back has Motorola stamped in it. I have 3 wires coming from the back of the alternator/regulator

they are a very large red (to starter solenoid) I believe
a smaller red one (to the positive terminal on the coil) I believe
and a tan one that sort of mystifies me. I believe it to be a ground but it is tan. I do not want to go hooking up wires and testing for fear of causing more damage. If someone could please help identify which wires connect to what terminals I would be greatly appreciative.

Thanks,

Max

 

[Splat]

Re: How Do I identify my alternator?

Ok normally the large wire will go to the positive side of the battery. This is where the battery will get it's juice for charging.

Now for the other two. I THINK
The red one should be your field wire coming off the rectifier. THis will need to be connected to the positive battery as well, this tell the alternator how much to charge. If it's not hooked up the alternator is dumb and will just sit there. Also if I remember correctly this wire needs to be switched off when the engine is off (like through a key switch), or you can insert a diode inline. This wire drives a coil or "field" in the alternator, when the alternator isn't charging this coil will remain energized and drain your battery if directly connected.

The tan should be for a warning light, or buzzer. This will set off a dummy light on the dashboard if the Field voltage becomes higher than the voltage coming off the rectifier(battery not being charged).

Have some one double check this but I believe it's correct.

Bill