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DIY vs Gm harness

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Old Oct 14, 2017 | 01:15 PM
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Default DIY vs Gm harness

Im planning my ly6 swap into Malibu and I want to ask for you guys to give me an opinion or some input.
I need to buy a harness and ecu, Im thinking the e38 since My swap is a 58tooth motor.
My issue is that an ecu (100$), harness (250$), rewire service (250), would put me at just about 700$. Ill still need all the sensors, Map, O2's etc etc. So I almost think Id better off just buying the controller kit from gm for 1100$ And eliminate all the headaches of piece mealing a kit together.
The only thing that would make it worth while for me to not buy the Gm kit is If I can do the harness myself. Im capable of it but not sure how involved it is.
So if any of you have done it please chime in and give me your opinion or advise. Thanks
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Old Oct 14, 2017 | 04:34 PM
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You might also check with SpearTech and others that do wiring harnesses. They can customize one to whatever your setup is.

Last edited by G Atsma; Oct 14, 2017 at 07:53 PM.
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Old Oct 14, 2017 | 05:36 PM
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There is no GMPP kit specifically made for the LY6 (is that a 6.0L?) so you would still need a tune. Also, the kits don't come with sensors, other than O2 and MAF.

Andrew
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Old Oct 14, 2017 | 07:54 PM
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Originally Posted by Project GatTagO
the LY6 (is that a 6.0L?)
Andrew
Yes, it is.
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Old Oct 14, 2017 | 08:10 PM
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Originally Posted by Project GatTagO
There is no GMPP kit specifically made for the LY6 (is that a 6.0L?) so you would still need a tune. Also, the kits don't come with sensors, other than O2 and MAF.

Andrew
The LY6 is a 58tooth 6.0 with vvt. Im eliminating the vvt and going with a Hot cam, an ls3 intake, so im basing the engine management and sensors on an LS2-LS3. Its just easier to do that. The GMPP kit comes with a harness, ECM, Maf, O2 sensors, the pedal, the bung for the O2's and Maf.
So in my original posting Im at about 700 buck plus the pedal is another 100plus. So im just trying to figure out if its just practical when you don't have anything to just buy the GMPP kit. Obviously if you bought a pull out and have a harness, ecm and most of what it ran with before then 250 for a rewire is a no brainer. Tuning is going to have to be done either way.
If I can save the 250 on sending the harness out then I can maybe see going with a used harness and ecm. Depending on how much work it is to modify the harness and delete what you don't want.
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Old Oct 14, 2017 | 08:18 PM
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Originally Posted by G Atsma
You might also check with SpearTech and others that do wiring harnesses. They can customize one to whatever your setup is.
Thanks I didnt check SpearTech, i just did and there pretty much right in line with the rest of them as far as cost goes. See right now I dont have an ECM or harness. So Im pretty much starting from scratch. Unless I can find an Awsome deal on a ecm harness combo Im looking at basiclly around 1k or close to it for a ecm, pedal, maf, harness, harness rewire, o2's. At 1k another 200bucks and get everything brand new in one kit maybe worth it? Thats kind of the opinion Im asking.
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Old Oct 15, 2017 | 11:06 AM
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Originally Posted by Dinosport
The LY6 is a 58tooth 6.0 with vvt. Im eliminating the vvt and going with a Hot cam, an ls3 intake, so im basing the engine management and sensors on an LS2-LS3. Its just easier to do that. The GMPP kit comes with a harness, ECM, Maf, O2 sensors, the pedal, the bung for the O2's and Maf.
So in my original posting Im at about 700 buck plus the pedal is another 100plus. So im just trying to figure out if its just practical when you don't have anything to just buy the GMPP kit. Obviously if you bought a pull out and have a harness, ecm and most of what it ran with before then 250 for a rewire is a no brainer. Tuning is going to have to be done either way.
If I can save the 250 on sending the harness out then I can maybe see going with a used harness and ecm. Depending on how much work it is to modify the harness and delete what you don't want.
I was in a similar situation when I did my L92 swap back in 2008. I had the engine, but nothing else. I ended up using the GMPP LS7 kit because I was using the LS7 cam in my L92. I did the VVT delete, added a LS3 intake package, etc...

It ran perfectly and needed only a bit of tuning due to being rich at WOT. Otherwise the tune was very drivable.

Andrew
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Old Oct 15, 2017 | 06:06 PM
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If you haven't already, this is something to peek at. http://lt1swap.com/geniv_harness.htm
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Old Oct 15, 2017 | 07:38 PM
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I used PSI Conversion harness and they supplied my ECU. Perfect. Started right up the first time. Customer service first rate from start to finish.
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Old Oct 15, 2017 | 09:13 PM
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I was intimidated by the job, but determined to DIY my harness because of the cost of other options. It ended up being pretty straightforward, and probably took me about 8 hrs of actual work.

I say pick up the stuff you need from a salvage yard, study the schematics, and go for it. www.lt1swap.com did my base tune for $75.
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Old Oct 16, 2017 | 07:53 AM
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current performance wiring FTW
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Old Oct 16, 2017 | 03:01 PM
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I reworked my stock LY6 truck harness and made a lot of changes to accommodate moving my coils to the firewall, a card-style MAF, ECM placement, etc etc. Getting the right connectors, terminals, and crimping tools took a lot of research and was rather costly, but I did very few wire extensions/splices - for almost all of the customized wire sections, I used a new length of TXL wire with new terminals on both ends. If you are just shortening and eliminating wires and you are okay with solder splices or butt terminal splices, reworking a harness that already has the right connectors will not be too difficult, just time consuming. I enjoyed doing the wiring myself but it did not save much money and certainly did not save time.
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Old Oct 16, 2017 | 03:08 PM
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If you are extending it, make sure you pull the harness tight and all the wires or the same length, or youll have to cut and shorten all the wires like i did.
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Old Oct 17, 2017 | 11:49 AM
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All good input guys thanks.
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Old Oct 17, 2017 | 01:15 PM
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By the way, this is the best tutorial out there.

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