# LS3 coils and alternator wiring on EMU Pro 8

**URL:** <https://community.ecumaster.com/t/ls3-coils-and-alternator-wiring-on-emu-pro-8/5360>\
**Category:** EMU PRO\
**Tags:** wiring\
**Created:** [March 11, 2026, 3:17pm UTC](https://community.ecumaster.com/t/ls3-coils-and-alternator-wiring-on-emu-pro-8/5360 "2026-03-11T15:17:13Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![TiLow](https://avatars.discourse-cdn.com/v4/letter/t/dbc845/32.png) [@TiLow](https://community.ecumaster.com/u/TiLow)\
**Post date:** [March 11, 2026, 3:17pm UTC](https://community.ecumaster.com/t/ls3-coils-and-alternator-wiring-on-emu-pro-8/5360/1 "2026-03-11T15:17:13Z")

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Hi,

as mentioned in the title, I’ve got two questions on how to wire an LS3 engine:

1. LS3 coils got seperate grounds, one is reffered to as low reference or signal ground. With original Chevy wiring those grounds go back into the ECU. So am I right to put these to the digital ground pin on the EMU Pro? Picture is from MegaSquirt

2. There are 4 pins on the alternator plug, I’m not sure about B and C:  
A - not used  
B - alternator turn on - switched +12V through ignition or switched to ground?  
C - signal to control voltage, auxiliary output on EMU Pro, set as alternator output at 100Hz  
D - Battery +12V constant to supply the internal regulator I guess  

Thanks in advance 🙂

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**Author:** ![ProperTuningOG](https://dub1.discourse-cdn.com/flex013/user_avatar/community.ecumaster.com/propertuningog/32/3481_2.png) [@ProperTuningOG](https://community.ecumaster.com/u/ProperTuningOG)\
**Post date:** [March 11, 2026, 3:25pm UTC](https://community.ecumaster.com/t/ls3-coils-and-alternator-wiring-on-emu-pro-8/5360/2 "2026-03-11T15:25:35Z")

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We run the LS style coil back to cyl head for ground and ref. Some coils we solder and pot, when doing so we push the 2 ground pins together and solder a single wire to them. No issues in all the years we have been doing this. There is also no need for a cap like the MS picture above.

With the 4 pin style alt, you realistically just need the Lamp, B, terminal to an incandescent bulb or IGN with proper resistor. The 2 pin hairpin style, thats a different story.