alernator not charging

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Mar 27, 2010
i have a sbc with a alternator from a 92 s10 blazer 4.3 and it dosent charge the battery theres a main bolt on the back labled battery so that one went to the battery then at the battom of the alternator theres a plug with a red and black wire were do these go ?
the motor is in a 1994 toyota pickup
Oct 24, 2009
Do you have a "charge Indicator" lamp or some other similar resistance item in the circuit? If not you need one.

No ya dont. Ya need to loop one of the wires on the plug to the charge terminal. Then it will self excite and charge.

Easiest way to tell if ya got it right (with no tester) is to see if a wrench or sumtin steel will stick to the center of the back of the alternator where the shaft/bearing is while its running. If its charging it will make a electro magnet out of the shaft/bearing and a wrench will stick to it.

If nothing, then no chargy.

I just put a late 70s-late 80 gm alternator in my ol 67 chevy truck last week. One heavy 8 gauge wire from the alt post to the battery and one 14G wire about 5 inches long with an insulated spade and a ring terminal to put on the power post and on to one of the two terminals you mentioned.

Ill have to go look at mine to see which one is the exciter.

You can do it with a gauge like mentioned above by medusa but its not needed.

You need to get a donor plug from a wrecking yard or parts store or get an INSULATED spade. If not the terminal can rub/spark on the alt case.
Feb 6, 2002
If it is a stock '92 alternator it is problably a CS130. It needs key on power to the L terminal, through a light bulb if you want a charge indicator light. The sensor lead is not necessary. If you put power from the B lug onto the L terminal, it will work, but it will drain your battery when off.


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