98 5.7 vortec swap to LM7 5.3l need wiring help

[RPM Graphics]

Thanks for all the good info. I noticed that you were looking at the weather sea,l with all the wires going through it. DId you have to remove any of the wires from that? I have got around to ripping the harness out yet. And did you swap the brake, check engine, and fuel pump wires from the old ecu to the new harness? And the 896 pcm will work right?

i didn't do anything to the brake wires. the new harness from Nelson came with an OBD2 port & light. i just tapped into the factory CEL so i have the one in the gauges & one under the hood. fuel pump just needed 12 volts that comes from the new harness.

i think i removed most of the wires on the passenger side plug. that plug is a little different on the 97/97 then the 96. that's how i realized i had the wrong year harness at first.

[shmiet]

Would you say it's easier to use both computers? that way i wont have to mess with the wires going into the cab etc correct?

[RPM Graphics]

i don't think so.

[shmiet]

I think I'm in way way over my head haha.

[RPM Graphics]

i thought the same thing. now i'm doing a swap into an IS300. it's really not that bad.

[Mickeymotormount]

Some wiring diagrams certainly help in these type of situations. Here's one for your truck:

http://www.ebay.com/itm/1997-Chevrol...bf542e&vxp=mtr

Not sure of the year of the new engine, but I would consider looking into getting one for that year as well to see what the differences are between the 2 vehicles for all the systems you are asking about; i.e. guages etc.

[Ian Johnston]

These projects are very daunting initially, but I found if I printed off as much info as I could find, and I was lucky to get a very good CD for the GEN111 vehicles(Aussie versions), that it made the job a lot easier. I did my own wiring mods, and found the wiring diagrams I had made it so much easier.
So, really it means plenty of research, and print as much as possible.
Certainly the 2nd conversion would be so much easier.