lq4 wiring help
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Joined: May 2014
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From: Grand Blanc MI.
lq4 wiring help Hello I am new here but have heard this website has alot of information. I am curently building a 72 chevelle in my rare spare time, the motor that will be going in it is a LQ4 from a supposedly 2003 2500hd, with plans of running a s475 turbo and just have a mild built th350 for now (money is tight) I will be stepping up to a 4l80e once I get the money around probably next year or so, or when the th350 fries haha. The computer that came with the motor has green and blue connectors, and the wire harness does not have a fuse box. I have looked around and could not find a full wire diagram just the pin out lists. Does anyone have a engine wire diagram I could use? would this computer be good for what I am doing or find one for a DBC red and blue computer with harness fuse box ect? Any info would be awsome, I am new to the whole efi stuff and definatily not a electrition so any information is helpful.
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Joined: May 2010
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From: Atlanta, Ga
Take a look at www.lt1swaps.com for the wiring harness guides. Do you have the DBW throttle body, pedal and TAC? If so there is no good reason not to use them. The PCM you have can be modded to DBC when the vats is removed. I do believe that some programing will be necessary to delete the trans controls. My best advice would be to save up your money and do the trans while you are at it. Even going to a 4L60E like lots of us have done is a huge upgrade from what you have. You may be able to offset the cost by selling your current combination.
None of this is rocket science. All it takes is patience and a willingness to learn. Be sure to ask questions before you tackle any jobs you are not sure about to save a bunch of time and money. Most of us are not here to judge you or your project, just to offer support and our experience.
None of this is rocket science. All it takes is patience and a willingness to learn. Be sure to ask questions before you tackle any jobs you are not sure about to save a bunch of time and money. Most of us are not here to judge you or your project, just to offer support and our experience.
Thread Starter
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Joined: May 2014
Posts: 7
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From: Grand Blanc MI.
Oldgoat69, thank you for the link and advice. The motor did not come with throttle body, gas pedal, fuse box, injectors, exhaust manifolds, and just water pump, harmonic balancer and brackets. The only reason I got the trans was because I knew the guy it came from and only paid $150 for it and the motor I picked up for $250. My plan was to just run it and start saving up money to upgrade when the th350 lets go, but upgrading now would save money in the long run, got some more thinkin to do now haha. You have a great looking car by the way. I am open to all sugestions since this is my first build and starting with a bare shell
I was in the same boat you were in last August.
My LQ4 came with a lot more than yours, but if you're going to turbo it, there is going to be lots of tuning anyway, so since you'll need all the right pieces, personally I'd go DBC.
Go to AutoZone or O'reilly's and get a repair manual for the wiring diagrams.
You'll want to cross reference at times with Lt1swap.com's pinouts for the right wire color.
If you're going to keep the TH-350, you'll possibly need 1" setback plates to not have to modify the trans crossmember...
If you build your own crossmember then you can use standard plates.
If you get rid of the th350 and upgrade, then you can pick out all your pieces to work together.
That th350 will collapse under boost... it might be sellable right now while it still works.
Also, you'll need a crossmember for the new transmission, so don't buy one for the th350 or you'll be buying two.
Like was said, read and ask questions. Don't throw money away just for the experience.
My LQ4 came with a lot more than yours, but if you're going to turbo it, there is going to be lots of tuning anyway, so since you'll need all the right pieces, personally I'd go DBC.
Go to AutoZone or O'reilly's and get a repair manual for the wiring diagrams.
You'll want to cross reference at times with Lt1swap.com's pinouts for the right wire color.
If you're going to keep the TH-350, you'll possibly need 1" setback plates to not have to modify the trans crossmember...
If you build your own crossmember then you can use standard plates.
If you get rid of the th350 and upgrade, then you can pick out all your pieces to work together.
That th350 will collapse under boost... it might be sellable right now while it still works.
Also, you'll need a crossmember for the new transmission, so don't buy one for the th350 or you'll be buying two.
Like was said, read and ask questions. Don't throw money away just for the experience.
Last edited by ryanleiker; May 14, 2014 at 10:36 AM.
Thread Starter
Registered User
Joined: May 2014
Posts: 7
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From: Grand Blanc MI.
ryanleiker, I already have dirty dingo slider mounts for it. Also leaning twards the DBC since its simple and less wireing haha. Yeah I am staring to shop around and resurching the 4l60e vs 4l80e right now. My plan was in the future do the trans swap and run a RMVB so I wouldnt have to worry about the trans wiring and computer. just wasnt sure on the computer since I have seen alot of people using the red and blue computer for DBC
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Thread Starter
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Joined: May 2014
Posts: 7
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From: Grand Blanc MI.
What transmission would you recommend 4l60e or the 4l80e? My harness already has the trans sub harness and prndl switch for the 4l80e but I can get a 4l60e out of a mid 90s truck for free just have to go to Florida and get it
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