Goldhawg

iTrader: (7)

Just picked up a new to me '99 2 door Tahoe. Of course I have LS plans in my future, but probably not for a couple of years if the L31 holds up (120k miles now). A popular upgrade that many have done is swap the stock PCM for an 0411 pcm since it controlled both L31 Gen 1 engines (in express van) and Gen III engines. This appears pretty simple, only requiring repinning and splicing into 4 tranny wires:
http://www.gmtruckcentral.com/articles/12200411.html
Since I will be close to stock I could probably do a simple mail order tune on existing PCM, but for just a bit more $$ I can have a much better ecu for tuning and be prepped for an LS swap.
I know the pcm can support any Gen III, and I believe I can support a Gen IV motor w/Lingenfelter's converter (58 to 24). So if I do this, I believe I can just swap over a few more pins and wires (such as the injectors and maybe even DBW) and use my existing 99 tahoe wire harness.
Am I correct on this? I hate wiring and the idea of an evolutionary approach and using mostly my existing harness is greatly appealing. What else should I be considering? If I do go this route, can I also do a simple repinning from the 0411 to another PCM at some point in the future if required (like maybe I'm able to get a Gen V motor in a couple of years). Thoughts?

Bo185

Read this
http://www.hotrodlane.cc/PDFFILES/Lisa%20Tahoe.pdf

It most liey would be easier and cheaper just to use a Gen IV ECM. With the 411 you would lose VVT for example.

Pacer Racer

iTrader: (6)

There are a lot of wiring differance between a 411 running a L31 and a Gen 3 motor. When you do the upgrade to a Gen3 you might as eell plan on a differant harness anyway. It would be a lot less work to modify a newer truck harness from a Gen3 motor to work in your chassis then to modify an L31 harness to run a Gen3 motor. You're looking at 8 coils compared to one, a differant lcation for the crank sensor, the IAC & TPS, and a totally diferant arangement for the injector wiring

Goldhawg

iTrader: (7)

That's a bummer. Ok another reason to stick w/a Gen III motor. Anything else? Since some Gen IV's come w/o VVT.

To Pacer Racer, you're probably right. However, it might not be too hard to pull out the wires for just those sensors/connectors that I wouldn't have in the L31 and add them to the 0411, and zip them into the loom. Certainly would be cheaper.

gofastwclass

iTrader: (2)

Have you compared the harnesses and engines? Time is money and I bet you would be time and money ahead starting with the Gen III harness. By the time you pulled out what you didn't need and tried to insert what you did in the current harness, you could have reworked the Gen III harness to standalone and fit it in the non-Gen III truck.

Just my opinion, but I believe there will be much more original wire on the ground than you think.

01cherryreds10

iTrader: (9)

I agree with them start with a Gen 3 harness. You never know what you are going to find in that harness you have now with that kind of mileage and you living in the Midwest. It's difficult enough stripping down a harness to run standalone let alone modifying your harness to work with the PCM

Bo185

Its not so much the VVT its the AFM. You have to remove the heads to delete it which is a pain. All the 2010-up truck motors are all VVT now. The 5.3's 2009-down are non VVT.