Is there a definitive wiring diagram for making the stock Toyota tach work after an LS conversion?
Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.
- E38 ECM; Chevrolet Performance NA LS control kit 19171935; LS2/LS3/LS376/LS7/LSX454; 58x/4x; 2006+: Tach output is a 2-pulse-per-rev square wave. (Chevrolet Performance)
- 0411 PCM (GM service #9354896 or 12200411); 1999-2007 Vortec DBC (LM4/LM7/LQ4/LQ9/L33/L59); T56 or non-electronic automatic: Underdash output wires: MIL, speedo, tach. (PSI Conversion)
- 0411 PCM (GM service #9354896 or 12200411); 1999-2007 Vortec DBC (LM4/LM7/LQ4/LQ9/L33/L59); T56 or non-electronic automatic: Tach must be set to 4-cylinder mode; AutoMeters may need a resistor. (PSI Conversion)
- E38/E67 ECM; Speartech 58x manual-transmission harness: Speartech white is tach, yellow is the electric-speedometer signal. (Speartech)
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
- LS Series Engine Control System Guide — Chevrolet Performance (via Scribd)
- https://es.slideshare.net/slideshow/har-1019-vortec-swap-wiring-harness-instructions-efi-conversion-fro/47382494 — PSI Conversion
- https://speartech.com/v/vspfiles/instructions/58xman.pdf — Speartech