mercruiser alternator question

IAMHOOKINGUP

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Joined
Jun 12, 2004
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2
I have a 1990 4.3l mercruiser I/O. Ther alternator recently died. I had it rebuilt. There are three wires that connect to it a thick positive red wire, and two others. The other two are an excitor and a sensor. The problem i that the exictor and sensor wires are the same color coming off the motor"whoever had the boat before me must have changed them" Is there a test that I can do to tell which wire is which?<br /><br />Thanks\<br />Al
 

Bondo

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Apr 17, 2002
Messages
71,306
Re: mercruiser alternator question

According to my book,<br />The Excitation Wire is Purple.......<br />Which mounts to the Port stud.......<br />The Sensing Wire is Red/Purple.......<br />Which mounts to the Starboard stud.......
 

navigator336

Petty Officer 1st Class
Joined
Jul 27, 2003
Messages
270
Re: mercruiser alternator question

It's an easy test. The sense wire should have 12 volts on it when the key is off or on. The excite wire will only have 12 volts on it when the key is on.
 
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