Am I nuts? LQ9/4L65E --> 98 K1500

[RY_1998Z1]

Nitrous and all,

Thanks! Nitrous, I am wondering what it takes to get rid of the 98's computer altogether and just run the 03's, well at least a modified version of it because I know I'll need the drive by wire stuff and security taken out of the program.

I have the pinouts for my stock computer and have been looking at them and see there are things like my transfer case hi/low, 4wd, AC compressor controls, fuel level sender, etc. in there and I don't know if the new computer can be wired to understand them (am I saying that right). Like if I can adapt my 98's AC compressor, can the 03 computer run it? Can I get my fuel gauge to work? The Caddy is AWD, but I'm going to swap my push-button 4wd T-case on the 4L65E. I don't know why the computer needs to know what the T-case is doing, but I also haven't gotten into this deep yet.

If I can impose on your time, can you hit me with highlights as to whether or not I can blow my 98 computer away? Keep in mind I have 100% of everything related to the powertrain in the donor. The harness is untouched and the engine starts right up! It's not like I'll be putting the newer motor in front of an older trans. It's the matched set, and looking at most of what the computer does, well, that seems to be it except those few exceptions. I thought there'd be ABS and stuff but I guess that's standalone.

[RY_1998Z1]

I was looking through their pdf catalog, are you guys talking about that ~$720 piece and doesn't have the new hoses???

WHOA! I need to figure out if I can get my old compressor slung! Going to need to look at that dual alternator mount for some ideas...

[Lextech]

Ry,
That post on PacificP.com about the 12200411 PCM is mine. You're right it is Loooong. That thread went in many directions that I have NO control over. The 0411 PCM is a complete replacement in the 96-2000 Distributored Vortec trucks with the Black Box PCM. The 0411 will run the Distributored Vortecs and Gen 3 engines if it gets the proper crank/cam inputs and is programmed to match. The Question is--Is your LQ9 a 512 or 1Meg engine? Does it have a 24x or 58x crank reluctor? The 512--24x engines use the Red and Blue connectors for the PCM and the PCM can be completely replaced in your truck, if so. I KNOW the 411 will run ALL functions of your truck properly, But I don't know if a newer 1Meg PCM will.

PS, I don't own a GEN3 truck, But I LURK here often.

Jeff

[NITROUS]

RY, talk to Richard Campbell. He has a 96 with a 6.0 with the exact setup you're wanting to use. In the meantime if I had a pinout of your pcm I would be able to tell you if it will run everything and I'm pretty sure it will.

[NITROUS]

Lextech, nice setup with the ramjet and all. I almost went that route before the LSX install but without the turbos. There's alot of good info in your post.

[RY_1998Z1]

Jeff,

Well, I don't know how to tell about the reluctor... I will pull the computer plugs when I get home to see what colors they are, but reading S&P's catalog last night, it seems I might have a computer that can only run drive by wire. I really want to just run a cable... I really need to see if the computer model number is on it someplace.

Nitrous,

How can I get the diagrams to you? I can scan them no problem.

[RedHeartbeat]

Get a cable driven wiring harness and pcm from a 99-2002 model. The 58x reluctor wheel came out with the LS2s. You can count the notches on the crank by removing the crank sensor and rolling the crank around 1/4 turn and counting the notches x 4.

[NITROUS]

Why don't you scan them to photobucket and then hyperlink them through PM's.

[RY_1998Z1]

I checked this morning during a break in the rain. The computer is #12582605 with blue and green connectors.

Nitrous, I scanned the pinouts at work and will see about getting them to you..

Thanks!

[Time2Kill]

I've got a LS2 with a 411 PCM in my '98 truck. I completely ditched the vortec PCM. I used a 5.3 harness from a 2001 truck, had to cut and splice to match it up to the fuse panel, to the connector on the firewall, and had to run some miscellaneous wires here and there. The 411 PCM outputs the correct VSS so that ABS and speedometer will work. Tach resolution can be changed in the PCM so the tach reads correctly also. I believe I used High 3 Low 2 or vice versa on the tach resolution. The only thing that will not work on the '98 is the fuel guage. I'm running a programmable Autometer gauge that works off the stock fuel sender. Works perfectly. Also, if you do the motor mounts correctly, you will not need custom parts anywhere, transmission lines, driveshafts, exhaust etc will all line up and be bolt on parts. Most conversion motor mounts move the engine back to far so everything needs to be custom made. My truck has been running for almost two years with zero issues.