OBS chevy LSx wiring

How are you guys running the two harnesses? What about ECS controls in the cab? A/C, tach, all the gauges, etc. Is everybody keeping the old computer hooked up and running the 0411 seperate? I'm primarily concerned with the speedo and tach.
I guess I just don't get how the two harnesses work together. I'm on a Macintosh right now, so sorry if the text is messed up...
Thanks.

Can I just remove the old harness entirely? But then what about the tach/speedo...ughhhh

current setup is GMPP350HO, TBI (90 lb inj's), AFPR, all the good stuff. DIY tuning

so guys are running two isolated harnesses, huh? One for the powertrain, then one for the chassis?

I bring up A/C because of the computer (7747).
I'm aware of standalone engine harnesses and that's great...but what about retaining my 1991 gauges and controls?
I hate macintosh computers

the only real thing I think I need to know from the LS1 computer is check engine, tach, speed
A/C switch too.

There's no need to run both harnesses that I can see. Your gauges are pretty much standalone, so you'll keep what's needed out of the c100 connector on the firewall and remove what you don't need. you can tie the C100 wires into the new harness for temp sensor, tach, oil pressure, tach, A/C etc. are you going to have a custom harness built or use the new one?

I'll probably use the one from the donor truck. A tad on the pricey side for a new one!! lol

So that big azz clump of wires on the passenger side firewall is the main harness, huh? And that's what I'll be splicing into, obviously. Cool.
So the computer (TBI) runs through there, also? In addition to the cluster? Yah, I think they all go through there. I'm all ears, man. Thanks for the reply.

I know I sound like an idiot, but I've never messed with the harness. I've ran a few wires and pinned the computer for e-fans, a wideband and a MAT sensor, but I drilled through the firewall for that.

You're doing good, no question is a dumb question. You should have heard me when I got started. LOL Some of the wires go through the C1oo and others go through the passenger side under the plastic cover. Just to be familair with everything trace the wires back from the engine, injectors, etc... back to the firewall and it will give you a sense of comfort. Greg RedHeartBeat) has done a pre 96 swap and can probably answer more of your questions. I've been messing more with with 96-2000 vortec swaps but they are pretty much basically the same except for the wiring.

i am putting the final toutches on my obs to lsx swap (98) i am only running one pcm the 0411. all of my guages work tach, spedo etc as well as all of the abs and 4x4 stuff.

Quote:

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Originally Posted by 98 4X4 burban

i am putting the final toutches on my obs to lsx swap (98) i am only running one pcm the 0411. all of my guages work tach, spedo etc as well as all of the abs and 4x4 stuff.

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nice job, man. yah, I figure the OBD1 stuff should probably mostly removed...wish I had a 96-up lol

The 0411 pcm is great compared to the older black ones.

the 0411 is the newer vortec pcms correct?

Yes, you're correct.

wow...I am totally lost. I wish one of you would come to my shop and just magically make this thing work....I hate wiring.

Josh