i am doing a swap for someone the harness is from a 87 trans am. When the harness was pulled they pulled the engine control part of the harness with the computer. What i need help with is the harness is missing the part that where it plugs into the firewall and im wanting to know How the engine control part gets power to it i want to utilize his old harness and mate them together But i need to know where i need to supply power to the engine control harness any help would be very much appreciated

 

See diagram
http://www.chevythunder.com/198689_f...dy_1227165.htm



the under dash harness that has the computer plugs and the engine bay harness that goes to engine ;
both join at the firewall plug

Do you have both harnesses?

 

i have the part i mentioned of the tpi harness and the harness from the car which is a 92 firebird 6 cyl.

 

Okay What i really need to know is there is a 2 prong plug coming down by the battery What is it for? Im really familiar with the camaros harness But this is a lot different the plug has 2 10 or 12 gauge wires that are orange and black in color i know on a camaro the 2 wires that color are for the injectors and a fuse goes in it and then there is a red 1 prong wise that supplies power to the ecu. But this harness Dont have the single red wire does anyone on here know What the plug is for and where its suppose to plug?