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How should I wire my LS swap — factory harness or aftermarket, and how do I fix a reported misfire?
- Use a 10-megohm digital meter, never a test light. (applies to 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. (applies to 0411 PCM (GM service #9354896 or 12200411); 1999-2007 Vortec DBC (LM4/LM7/LQ4/LQ9/L33/L59); T56 or non-electronic automatic)
- DTCs are read through the harness DLC; codes clear after 3 minutes on battery disconnect. (applies to Gen III PCM; Aeroflow AF49-1505; LS1/LS6; DBC; 4L60E/4L80E)
- PCM plastic case is intentional so it grounds through the harness. (applies to Gen III/IV standalone swap harness)
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Confirm against the instructions for your exact parts before wiring. More: Harness and power in our tuning guide.