1968 Firebird/LS2 wiring issue

[Fourmz]

I have a 68 firebird (originally v8 w/ac) i have installed an LS2 from an 05 GTO with a CBMMotorsports engine harness and American Auto Wire bulkhead harness. I have started the engine by jumping it off of the battery so I know the ecu and engine harness are good. My issue is, i cannot determine how to marry the LS2 engine harness to the existing wiring harness on the car. I have the correct diagrams but still cannot connect the dots. Any pointers out there?

[andrewb70]

What connections does the CBM harness need?

Andrew

[rickpaw]

^^^ Like Andrew said.

On my PSI wiring harness, it needs 2 grounds, 1 constant 12v, 1 ignition 12v hot. I used the pink wire (coil wire) from AAW wiring kit for ignition hot, and used the starter post for constant 12v.

[DIY TA]

Assuming that you have the fuel pump relay system figured out, if it's an auto trans you need to tap into your brake light switch to apply 12v when the brakes are applied (E40 ecm and T42 correct?). There's two wires there for an auto. One for ecm and tcm. Your aftermarket harness should have leads for speedo, tach, check engine light, OBD, hopefully a temp and oil sender, plus all the power wires previously mentioned. Cruise adds more to it. I'm running the same 05 gto ls2. Hope this helps.