LS3 ECU and Factory harness

[ebeck]

Just trying to wrap my head around the ECU wiring, if you order a GM crate LS3 how does the ECU connect to the factory harness for gauges, check engine, rpm speed etc... I know GM also sells a harness for installing the motor in non LS cars but I imagine it is too short, do you lengthen the wires and then work out the pin outs and graft it in your self or is there a connector harness ready to go somewhere?

[ebeck]

I suppose the question is WHO sells a harness. GM sells one but it is too short and it may not have same connectors as what is on the Ultima harness. If American speed sells them stand alone (I hear they are labeled and jsut plug in) along with the accessory kit for AC & Alternator then that simplifies the issue.

Who else sells an accessory kit & LS3 harness over on your side? I saw Auto Bionics or Boost Performance may?