Alternator wiring for 66 Sprite

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Alternator wiring for 66 Sprite

Postby rob66sprite » Thu May 03, 2012 11:48 am

I am restoring a 66 Sprite that had almost no wiring when I bought it. Since I have an electrical back ground I was comfortable wiring the car by building my own harness. I am happy with everything but the alternator and everything else works wonderfully. I bought an alternator for the 72-79 Midget from Moss. There are 3 pins coming from the alternator, a smaller one and 2 larger ones. The 2 larger ones appear to be jumpered in the alternator housing connector. I am not familiar with car alternators but they seemed simple. While idling the car I can not disconnect the battery without the engine stopping right away. With the alternator wires disconnected and the engine running I did not get any voltage from any of the pins. The alternator case is .6 ohms to chassis ground. The wires also ohm out without error. I thought the smaller pin would go to the indicator and the larger pins would go to the battery side of the starter solenoid. I took the alternator to AutoZone and it passed the tests with their testing machine. Some cars have alternators that need to get a signal from the ignition to begin providing power. Is that true for this model? I found a diagram for the 72 MGB that shows both larger pins going to the solenoid and the smaller one going to the indicator.

Thanks in advance,
Rob
66 Sprite (work in progress)
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Re: Alternator wiring for 66 Sprite

Postby rob66sprite » Thu May 03, 2012 5:43 pm

This alternator did need a "start" signal. I ran the indicator (smaller pin) to the indicator light and then to 12V and the alternator began providing power and I was able to disconnect the battery and continue running the engine. So in summary, the 2 larger pins are wired together to the battery side of the alternator to provide charging and power to the car while running and the indicator pin went to the light and then to the power from the run side of the ignition.
Rob
66 Sprite (work in progress)
www.facebook.com/rob66sprite
rob66sprite
948cc
 
Posts: 65
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Re: Alternator wiring for 66 Sprite

Postby Charlie Tolman » Fri May 04, 2012 12:53 am

Good job ! Charging circuitry can be challenging and confusing. (unintended alliteration)
CT
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