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Where do I feed the main 12V battery power to wake up the factory interior fuse block when the stock engine harness is gone after an LS swap?
- Minimum 8-gauge wire for the fuse-block battery stud. (applies to E38 ECM; Chevrolet Performance NA LS control kit 19171935; LS2/LS3/LS376/LS7/LSX454; 58x/4x; 2006+)
- LSA fuse/relay center has 50-amp fused accessory studs. (applies to E67 ECM; Chevrolet Performance LSA E-Rod control system 19299067; LSA)
- Two large black ring terminals supply constant battery power. (applies to 0411 PCM (GM service #9354896 or 12200411); 1999-2007 Vortec DBC (LM4/LM7/LQ4/LQ9/L33/L59); T56 or non-electronic automatic)
- Speartech orange 12-awg feeds constant 12 V to the ECM, ALDL and fuel-pump relay. (applies to E38/E67 ECM; Speartech 58x manual-transmission harness)
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Confirm against the instructions for your exact parts before wiring. More: Harness and power in our tuning guide.
Feed chassis power through the C100 connector. Two 12 AWG red wires carry all of the chassis power: Fusible Link A runs the lighting, and Fusible Link B runs the dash and HVAC fans. Cut off the fusible links and tie both wires into your new power distribution. A used 90-92 engine harness is the cheapest source for the engine-side C100 shell (Aptiv 15492519). The Metri-Pack 630 terminals (12064735-L) cost under $5 each. If you use a fuel-pump hot-wire kit, trigger its relay from the engine harness signal, not from plain key-on power.
Check this first:
- Both 12 AWG red feeds are identified at C100
- The new power distribution fuses the lighting and dash/HVAC feeds
- The fuel-pump relay trigger comes from the engine harness signal
Careful: Once the fusible links are gone, those two feeds need proper fuses in the new power distribution, or a short can start an electrical fire.
Based on what we've seen work across our own builds, our friends' builds and the wider LS community, reviewed by our lead shop tuner (over 20 years of LS and LT tuning experience). Every combination is different, so use at your own risk and check our safe tuning limits before any wide-open pass.
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Every option we know of
| Maker / product | Part # | Fits | Price | Where | Status / notes |
|---|---|---|---|---|---|
| Aptiv / Delphi Metri-Pack 630 male terminal, sealed, 16-14 AWG | 12064735 (verified) | C100 connector power feeds | about $0.50-1 each | Mouser, Waytek, Terminal Supply | Current production Confirm sealed variant for engine-bay use |
| Aptiv C100 connector shell (unverified lead) | 15492519 (not independently verified) | 90-92 engine harness C100 | varies | dealers, Mouser | Unverified Verify against actual connector |
| Junkyard Used 90-92 engine harness (C100 pigtail) | n/a | Correct shell + terminals guaranteed | about $20-50 | wrecking yards | Yard dependent Cut long pigtails |
Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.