LS Swap Help: Wiring

Engine Wiring Harness:

There are three main options for getting your engine harness and computer setup. 

  1. Purchase a brand new harness from an LS conversion specialty company and send them your computer to get tuned. We recommend, BP Automotive,  PSI Conversions or Speartech Wiring, but there are many companies. 
  2. Send your factory LS engine harness and computer to an LS conversion specialty company to get reworked and tuned for your application.
  3. Rework the harness and tune the computer yourself. This is not recommended for the average user. But, if you're the kind of person who will take this route, then you're probably not reading this page.


4L60 Transmission Pin Diagram:

Pins A & B:
NOT used.

Pin C connects to: 
Computer Harness Ignition (Pink wire)

Pin D & G connect to:
Computer Harness Ground Wire

Pin F connects to:
Scout Reverse Lights Output (Brown wire)

Pin E connects to:
Scout Neutral Safety Wire (The middle wire on the Scout transmission harness plug)



Brake Light Switch Diagram:



3rd Gen (2003 – 2006) LS Engine Fuel Injector Styles: 


Speedometer Cable Converter Diagram:

  1. Connect the WHITE wire to the signal wire.
  2. Connect the BLACK wire to the battery ground. 
  3. Connect the RED wire (through a 5 AMP fuse) to the engine side of the ignition switch (+12v 'hot' when the key is 'on'). 


Please Note: This page of LS engine wiring information will continue to develop. So please be sure to check back for updates. 

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