5.3L swap wiring help needed

[scott_williams2]

So I plan to do a LS swap in the near future on my 97 k1500 it has the 5.7L vortec in it now with a 4l60e. Where I am u can get a somewhat low mile 5.3 with harness and ecu for a little under 1000. I have a pretty good understanding of how to make the swap work physically and mechanically but pretty stumped as to wiring. Do I need to overhaul the old computer and harness and just use the new computer and harness? How will I get my gauges to work? Will the new harness be able to electrically run my old transmission?

 

[stutaeng]

LT1Swap.com has an entire section on his website that covers GMT400/LS swaps.

You use the new computer. Don't really know about the guages. He's got a video on YT where he sort of merges the 2 wiring harnesses.

And the transmissions are basically identical electrically, so no problem at all with controlling it.

 

[scott_williams2]

LT1Swap.com has an entire section on his website that covers GMT400/LS swaps.

You use the new computer. Don't really know about the guages. He's got a video on YT where he sort of merges the 2 wiring harnesses.

And the transmissions are basically identical electrically, so no problem at all with controlling it.

Ok thanks that makes me feel more confident I’ll go watch his videos and see how hard it can be. Worst case scenario I’ll just send it off to someone to do

 

[stutaeng]

Yeah, folks do this in some areas locally or by mail order.

You need both vehicle pinouts. If you can trace one wire, you can do an entire harness.

I've got 2 harnesses in my garage right now. A 4.3 Silverado and a donor 5.3 L59. When I pulled the L59, I foolishly cut off the tranmission harness. So I have to steal the corresponding wires from the 4.3...