2001 4.3l to 5.3l

[phoenix19l]

People I need help!!! I am trying to convert over to a 5.3 in my 2001 xtreme. I have the engine, wiring harness, PCM, and transmission. Waht else will I need? need to do? Will the wiring harness from the v8 suffice or will i have to get a conversion harness? Ive heard that I need to notch the frame to make it fit. If so, where and how far? What engine mounts should I use? the 2.8 mounts with that adapter mount? or will the original v8 engine mounts work? This is my first swap, so Im trying to ask questions so I get it right the first time. Or at least close to being right the first time. Any help is appreciated. Thanks guys

[Rinkrat456]

Do your research for a few months. Not a single person on here with Gen III motors sitting between the frame rails did a swap over night. Many of us took half a year at least to plan, probably more. Grab a case of beer, put in your favorite music CD and start reading.

[asepmaster]

Do your research for a few months. Not a single person on here with Gen III motors sitting between the frame rails did a swap over night. Many of us took half a year at least to plan, probably more. Grab a case of beer, put in your favorite music CD and start reading.

good advise. most of a gen 3 swap time is research. search old threads with specific questions. good luck

[phoenix19l]

Got the beer and some random CD...Back to researching.

I have found most of the information that I needed besides the wiring. Yes, I could spend the $900 to buy the conversion harness, but I have both harnessess (4.3l and 5.3l). I have to beleive that there is a diagram that will show how to splice the two harnessess together to make one good converted harness. DOes anyone have any idea where I could find this conversion harness diagram?

[Rinkrat456]

Keep in mind that good harnesses can be sold for $100-150 on classifieds, so if you sell both of yours you could have $200 or more towards a Current Performance harness. I am a mechanical engineer, not an electrical engineer, so I build the fun stuff and let professionals do the wiring for me. :-)

[Ryoung68]

Good Luck and take pictures of the build. Get a good schematic of both vehicles first and then decide which circuits you need. Then start splicing. :wtf:

[carshop]

There is really not a "one fits all diagram" I would highly suggest you pack a lunch for a few weeks and buy the harness that is built specific for your swap...

[phoenix19l]

I have come to a decision. I am going to send my off. I figure I might as well do it right the first time and learn how to convert the wiring later.

[Rinkrat456]

You can run the motor on the stock 5.3L tune without a problem, it just wont be dialed in if you change the cam, compression, heads, ect. If all you do is swap in the 5.3L and leave it alone, there's no real urgency to tune the PCM. I've had Current Performance make me two harnesses now with great success, I just don't like how expensive their tunes are, nor will it be spot on for your build. It will be a "one size fits all" tune, and for the money they're asking, I don't think it's worth it.

[phoenix19l]

I dont plan on changing anything in the motor(well not in the near future anyway). I am perfectly content with the 285 hp and 300 tq. If it will run on the stock tune then i just wont get it tuned. Will the stock 5.3 harness work ? if not, what has to be modified? If it is simple stuff then I might just do it myself

[Rinkrat456]

As I said earlier, I am not an electrical engineer. I can jumpstart a car, wire up a decent audio system if I have color coded map to follow and I can even wire up an electric fan like I did this past weekend. I was so proud of myself! haha. As for splicing 2 complex harnesses into 1 and expecting the gauges, ignition, starter, fan(s), trans and all the sensors to work.... HA!....not a chance. I leave that to people with prior experience and expertise. I bought my two Current Performance harnesses over the years and plugged them in. With my truck being the older of the 2 projects I've completed, I had to splice into my current V6 computer a bit to make the gauges work I assume, but I had color coded instructions and Current Performance on the telephone while I did it!

Asking me for help on wiring is like asking a blind & deaf person if he heard the back up siren before the dump truck backed over and killed him.

At any rate, if the stock 285hp/335tq is fine for you, don't have Jared tune it. Just order the harness and plug it into your computer.

[phoenix19l]

Thanks rinkrat. Thats actually some beneficial news for me. If I plug the stock 5.3 PCM in will it run all of my accessories without a hitch?