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LM7 Alternator Wiring

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Old Jan 7, 2017 | 04:31 PM
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Default LM7 Alternator Wiring

I have an LM7 alternator and a 3 wire clip. I have a 470 ohm resistor on pin B and am going to hook up pin C to 12v. Can anyone point me in the right direction or have any pointers. I bought a harness already and it didn't have the alternator wiring. So in a way I guess it would be similar to a carb setup. Any help is appreciated and thank in advance.
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Old Jan 7, 2017 | 09:31 PM
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If youre using the GM fuel injection and pcm, i would wire it up just like stock and let the pcm control it.

Iirc theres no need for resistors or bulbs with factory pcms. If you are carb or microsquirt etc youll need the resistor or bulb. Theres hundreds of threads on this subject also if you search.
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Old Jan 9, 2017 | 07:57 AM
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Originally Posted by seanb128
I have an LM7 alternator and a 3 wire clip. I have a 470 ohm resistor on pin B and am going to hook up pin C to 12v. Can anyone point me in the right direction or have any pointers. I bought a harness already and it didn't have the alternator wiring. So in a way I guess it would be similar to a carb setup. Any help is appreciated and thank in advance.
I'm using the 3 wires also except im not running it through the pcm. So I'm turning off all alternator related codes in the tune. My L terminal gets 12v ignition w/560 ohm 1/2 watt resistor. F terminal is the return from the dash light. The S terminal is the sense wire. This wire goes right to the junction post where the big Alt wire gets connected to, battery gets connected to, and anything else that gets charged from alternator. The S terminal wire should b 16 awg on the connector side soldered to a 20 awg fusible link with a ring terminal for connection to junction block.

If u use the pcm you do not need the resistor as was stated in the previous post. U can still use the sense wire and run it the same way.
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Old Jan 9, 2017 | 08:02 AM
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Originally Posted by jayyk31
I'm using the 3 wires also except im not running it through the pcm. So I'm turning off all alternator related codes in the tune. My L terminal gets 12v ignition w/560 ohm 1/2 watt resistor. F terminal is the return from the dash light. The S terminal is the sense wire. This wire goes right to the junction post where the big Alt wire gets connected to, battery gets connected to, and anything else that gets charged from alternator. The S terminal wire should b 16 awg on the connector side soldered to a 20 awg fusible link with a ring terminal for connection to junction block.

If u use the pcm you do not need the resistor as was stated in the previous post. U can still use the sense wire and run it the same way.


https://ls1tech.com/forums/conversions-hybrids/779728-thee-alternator-faq-thread.html
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Old Jan 9, 2017 | 08:51 AM
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The sense circuit is not needed, no need to use it at all.

The field circuit is not required.

The lamp circuit is required, hook to PCM C2 15 or to ignition through a resistor, as you are planning.


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Old Jan 9, 2017 | 07:18 PM
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Thank you everybody. The Lamp circuit is the brown wire. Correct? And I thought I read somewhere that it needs 12v power, and resistor to ignition
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Old Jan 9, 2017 | 07:42 PM
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Thank you everybody. The Lamp circuit is the brown wire. Correct? And I thought I read somewhere that it needs 12v power, and resistor to ignition

Last edited by seanb128; Jan 9, 2017 at 08:14 PM.
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