96 Z71 to 04 LQ4 6.0 wiring

**Dmixon13** · 06-29-2015, 08:12 PM

Ok guys I have a 1996 Chevy ecsb. I have put in a 2004 LQ4 6.0 today. Can anyone give me some help on the new wiring for this? I have the wiring harness, computer and drive by wire that came with the 6.0. I need to know how to get all this wiring hooked up to get this beast purring. Thanks for the help in advance.

**pajeff02** · 06-30-2015, 03:32 AM

Your best bet is to obtain schematics from the service manuals for both the truck and the LQ4. I do not have either in my collection unfortunately.

**Firebirdjones** · 07-02-2015, 04:55 AM

Jeff is right, you'll need schematics for both vehicles and alot of time pinning everyting out.

Anymore I just buy new custom made harnesses from Howell for the swaps I do. Plug and play, custom tune done, etc..saves me a ton of time.

**Dmixon13** · 07-02-2015, 05:01 AM

I found a guy that's going to graft the 5.7 harness into the 6.0 harness. He says that it will plug up to the rest of the wires that were left in the truck, I sure hope so. Thanks for the info guys.

**5.0THIS** · 07-02-2015, 07:36 PM

I'd rather spend the money with someone like painless and let them deal with the wiring nightmare.

**Dmixon13** · 07-03-2015, 01:54 PM

I called painless but they said that harness is around $900. I found a harness builder grafting the two together for about half the price.

**pajeff02** · 07-03-2015, 04:33 PM

Ensure that he includes wiring up the OBDII port connection for future diagnostics.

**Dmixon13** · 07-03-2015, 04:39 PM

Thanks for that info pajeff02!

**5.0THIS** · 07-03-2015, 11:33 PM

Originally Posted by Dmixon13

I called painless but they said that harness is around $900. I found a harness builder grafting the two together for about half the price.

You're paying for the fact that they've done it many times over and will get it right the first time with all new stuff and weatherpak connectors. No offense to the guy that's doing it for you, but he probably wont get everything right on the first try.

**Firebirdjones** · 07-09-2015, 02:05 PM

$900 isn't bad considering it's all brand new, plug and play, no problems.

Last thing you want is electrical gremlins on a new build that will have you pulling your hair out. The biggest issue with grafting wire harness together is that you are dealing with 15-20 year old wiring that's brittle, corroded, and high resistance issues aren't out of the question. That's assuming your wire guy gets everything connected correctly, that could be another issue all in itself.

I generally buy the harness, computer with custom tune, new 02's, new MAF, fuel pump setup with regulator, it's own fuse box complete with relays to run fuel pumps and fans, and OBDII light and diagnostic port....and main harness as long as I want it to hide the computer anywhere I please...all from Howell for $1500. This includes wiring in electronic cruise control for the drive by wire setup, and any custom electric fan setup I plan to run. Everything labled and ready to plug in with factory weather packs. It's really the only way to go with these retro swaps, trouble free.

Best of luck.

**5.0THIS** · 07-09-2015, 11:04 PM

Agreed. For 900$ painless couldn't have taken my money quickly enough.

**Dmixon13** · 07-15-2015, 01:34 AM

Ok got another question. Been reading about the inline returnless fuel system. Read that in 2004 GM went to returnless on the Vortec 6000 models. So does this mean this LQ4 does not have a return line and I'm going to have to get a fuel pump with a regulator built into it for this application to work properly?

**pajeff02** · 07-15-2015, 02:27 AM

Good question. You will need a method of regulating fuel pressure irrespective of whether or not it has a return line. You can simply add a separate adjustable regulator in line and set it for 58 p.s.i.

Like this: http://www.summitracing.com/parts/aei-13301/overview/

(By way of example only - not saying this is the exact one to use)

**Firebirdjones** · 07-15-2015, 04:30 AM

Yep, you'll need to regulate it. I use Howell's regulator, again included in the price I mentioned above was a pump and inline regulator setup.

There are many versions out there, some expensive and some adjustable. I liked Howell's setup because it was a simple check ball and spring that you mounted inline and regulates a perfect 58 psi.

Some people like to use the corvette fuel filter that has a regulator built in. I prefer to avoid that because those filter setups are $50-$60 around here. I didn't want that expense every year when I simply wanted to change a fuel filter during regular maintanance intervals. So I used Howell's regulator and then integrated my own 4th generation fuel filter in the system, simple $8 filter is much cheaper to change

**Dmixon13** · 07-15-2015, 07:20 AM

Well this is my first for all this and I'm def learning some stuff but also finding out how pricy all this can be. So yall are saying there is no return on this motor correct? And the only way to regulate it is with what yall have recommended ( some type of regulator). Another question. Will all the trans cooler and oil cooler lines hook up with this 4L80E like the 4L60E? Also, have to relocate AC compressor to the top so the mount plates could be placed in the appropriate spot. Relocation kits available to use factory compressor or no?

**Firebirdjones** · 07-15-2015, 07:53 AM

Yup, LS swaps definately are not cheap.

I get my AC relocation brackets from Kwik Performance, about $200 for the kit. It also requires a certain Sanden AC compressor so the original GM won't be used. The relocation kits use the Sandens and there are various locations for the ears to mount them depending on the accessory drive you are starting with, that will dictate which kit you need. Once you have the kit, instructions will give a list of part numbers for Sanden compressors that will fit. Once that's all ironed out then you get to spend money on having new AC lines made

See how this crap just steam rolls along? It's a domino affect.

Trans cooler lines are different between 4L60 and 4L80. Connection style is the same quick disconnect but the locations are different between the 2 transmissions. If you are lucky you might be able to tweak the lines without kinking but I've always found it better to start with lines that are made for the transmission being used first, then work with it. I just buy them at the local dealer.

**Dmixon13** · 07-15-2015, 07:56 AM

Say I went without the AC for a while, don't just pull all the AC components out?

**Firebirdjones** · 07-15-2015, 08:02 AM

You certainly don't have to have AC if you don't want it. That's up to you. It's not a necessity.

You can take off the factory stuff from the engine and just not run it, and if later you decide to make it work, the Kwik Performance relocation kit can easily be added later down the road. It mounts right in front of the passenger side head.

Also those kits require a new belt that runs everything, rather than the factory setup that has the AC belt seperate. The kit will give you the size in the instructions, so that's another $40 expense when the time comes.

When it's all over, relocation kit, sanden compressor, new lines, new belt, you'll have about $600 in that alone depending on what your local shop charges to custom make AC lines. Then a new dryer, R134 conversion if it's an R12 system, suck it down, charge it up. Another ~$200.

Depends on if it's worth that much to you, to stay cool.

**Firebirdjones** · 07-15-2015, 08:07 AM

Here's a pic of how it would look.

**Dmixon13** · 07-16-2015, 04:28 PM

When I get this thing running I will only have the exhaust manifolds on it. Will it be safe to drive to the muffler shop to have the exhaust put on or do I need to pull it? Have heard just don't hammer for risk of blowing out seals and to pull it. What do yall recommend?