How should I wire my LS swap — factory harness or aftermarket, and how do I fix a reported misfire?
Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.
- 0411 PCM (GM service #9354896 or 12200411); 1999-2007 Vortec DBC (LM4/LM7/LQ4/LQ9/L33/L59); T56 or non-electronic automatic: Use a 10-megohm digital meter, never a test light. (PSI Conversion)
- 0411 PCM (GM service #9354896 or 12200411); 1999-2007 Vortec DBC (LM4/LM7/LQ4/LQ9/L33/L59); T56 or non-electronic automatic: Unused wires are taped individually and secured. (PSI Conversion)
- Gen III PCM; Aeroflow AF49-1505; LS1/LS6; DBC; 4L60E/4L80E: DTCs are read through the harness DLC; codes clear after 3 minutes on battery disconnect. (Aeroflow Performance)
- Gen III/IV standalone swap harness: PCM plastic case is intentional so it grounds through the harness. (LSX Magazine)
Confirm against the instructions for your exact parts before wiring. More: Harness and power in our tuning guide.
Confidence: medium — sources disagree or are limited; check the sources below.
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Sources
- https://es.slideshare.net/slideshow/har-1019-vortec-swap-wiring-harness-instructions-efi-conversion-fro/47382494 — PSI Conversion
- https://aeroflowperformance.com/pub/media/Instructions_PDF/AF49-1505.pdf — Aeroflow Performance
- https://www.lsxmag.com/tech-stories/plug-in-play-installing-a-standalone-harness-for-an-ls-swap/ — LSX Magazine