LS Swap Harness Wiring Details: Where the Main LS Wires Go In 12 MINUTES
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- čas přidán 16. 07. 2024
- In my last video, I covered the wiring harness modifications for a 1991 Chevy OBS truck. In this video, I cover, in 12 minutes where I connected the main wires to make the truck run and its gauges. In the future, I will cover the twin electric fan wiring, cruise control, a/c and DBW connections. I hope this helps you with your swap. No 2 swaps are exactly alike, so this should give you a direction to get you started. Good luck with your swap!
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#lsswap #lsobs #obs #88-98chevytruck #ls - Auta a dopravní prostředky
This is the first channel that had explain the situation that I’m in trying to get the wires correct so I decided just to subscribe due to the fact this guy is a genius❤
Thank you! Good luck on your project.
ALL OF US CUHS N EDGAR'S APPRECIATE THIS VIDEO🙏
Thanks man seriously, the only other videos I could find have been grainy only explains like half of It
Thank you for making these videos, i also have a 1991 so this is extremely helpful
Glad to help
I really find the videos helpful and good ideas for my project 89 chevy I got. Keep up the good work and content
Awesome! Thank you!
Thank you very much. Very helpful information.
Very helpful! I appreciate you for this I’m doing one on my 92
Glad it helped
Good job fella keep going
Thanks. Very helpful and to the point.
You're welcome!
Bless you sir
Thank you!
Thank you, LS Einstein I got her running😂😊😊
Awesome, Congrats!! Puts a smile on your face doesn't it? Thank you...
Just what was missing. Mines a bit different but I like to see how others are doing it.
This is really helpful sir thank you
I recently just came across this channel but you are making this look like such a breeze but I am very curious about 4pin fuse block with the two relays idk if I missed that video but would love to know more about that
I did cover that in the previous wiring video, but I would definitely make some changes there. Check out my video on wiring in the a/c fan relay and twin fans. That box I got off of Amazon and it holds 6 fuses and relays. Even in you think in the beginning you don't want electric fans and want to run the clutch fan, I would wire them up with the needed relays etc. Then if you still don't want to use them fine, set the box aside with the wires. IF you change your mind at any time, it is all ready to go. Easier to do while you are doing all the rest of the harness. But, back to the main fuse block with 3 relays and 4 fused, use a weather proof moisture resistant enclosure. Under your hood can get wet and this will protect the fuse/relay box from both sides. The type setup you find on most installs is NOT moisture proof and can be a problem down the road. You can get electrical issues that could be caused by some minor corrosion that happens in the unprotected box and tough to track down. The better box is $20, an excellent investment. They look good and next vehicle I will use 2, one for the main harness, and one for the fans and/or a/c relays. When you buy electrical parts such as pins and small parts, buy more than you think you need. If you need 4 and you buy 4 I can almost guarantee you will damage one somehow (or drop it into neverland) and you will be one short. I can get them off Amazon for literally pennies each, so, buy a dozen or more. You will be glad you did.
Curious to know why you mounted the battery on the driver's side. My 94 has it on the passenger side. BTW, the videos are very helpful!
Thank you, I originally placed the battery on the driver side because my intent was to transfer all the original parts from the donor Suburban under the hood of the '91. Packaging became an issue and I abandoned that idea. I do like the idea of driver side battery for possible turbo installation in the future, gives more space for turbo and keeps the heat away from battery.
Great videos! Do I need the 5 volt reference or low reference coming from the fuel pump to make the gauge work?
I just made sure all the grounds were good and that’s it. The wires for the gas gauge are not in the engine harness.
I hope you have a bigger wire from the alternator to either the starter, or some other way to charge your battery, besides that little 12 guage going to the OBS block, or your not charging your battery.
I am using the same factory wire that was on the truck to the original alternator. Did the same with the '95 I swapped with no issues.
What transmission you use for your engine I have 91 also but I’m having a lot of trouble trying to find right one but your video would help me a lot
I am using the original 5 sod. trans that came in the truck. It is a 5lm60. You can use any trans you want, but you will want to research specifics for using that trans. to be sure you have or can get those pieces before you begin your swap just so it goes smoothly with no unnecessary delays.
Nice video. Im wiring a holley terminator and want to make a 12V switched power busbar. Where do I get the main feed switched power to power the bus so its not overloaded?
I used the factory bar. You have a lot of options new, but, you could just get one off of a 88-94? GM truck.
Is the large pink wire off the LS side running back to your 4 15a fuses? Or is that a different wire?
There is a pink wire that does provide power to the bus for all fuses.
I have a question sir I am also doing a ls swap in a 1993 GMC Sierra with a 6.0 with a 4l80 I was wondering where I connect the fuel pump wire that come out of the ls relay do i connect it to the junction block or directly to the wire and if I do have to connect it to the wire directly which wire do I cut and slice into gray or purple ?
From LS harness, I ran mine to the 3rd stud on the left of my power bus above the a/c accumulator. I believe that was where my OBS fuel pump wire was as well.
I was told to cut the fuel pump relay off of the stock 350 harness n to hook the gray wire off the fuel pump pigtail to the Ls fuse box do I need to hook it back up to 350 harness
As I did mention, this is how I did it and there are other ways it can be done. You can totally remove the obs wiring, or tap into it and run it the way I did.
What color is the wire that engages the starter on the LS engine, I’m in the middle of figuring out what wires are what
Usually a purple wire. Runs from ignition switch to solenoid.
Bout ready to do my first one, little scared, (going in to a 93k2500) have full donar of 05 suburban no mechincal fan only electric, this video saved, to help get the dash stuff to work, how about the obd2 port? how does that work?
When your new harness is made (either by yourself or someone else) an OBD port will be part of it so you can still check for codes or other issues. Check lt1swap.com site for wiring. Lots of great information there even if you choose to have someone else make a harness, you can familiar yourself with what stuff is and where it goes.
@@laurencevillegarage Wow didnt expect a response, thank you , a cup of coffee for you
Good evening sir. So you spliced into the dark brown(solid) 5:40 from the obs harness for the MIl light to work correct ?(i have 91 obs)
Yes, correct
@@laurencevillegarage ok, thank you. You have a good one👍
Do you have to leave the stock computer(pcm) in the truck along with the new ls computer?
It all depends. It will depend on how your truck is wired. Does it need the OBS pcm to run? No. But, the computer does handle other functions and you may want/need to keep it to handle those functions. I suggest NOT cutting anything until the new swapped motor runs. THEN, make sure all the features you want to function do, gauges, etc. THEN, start thinning out and removing those old wires. You many find you need a few to keep working. Remember to keep some notes on what you do. Someday, down the road, you or a new owner may need to fix an electrical issue and with no notes or clear way on how the truck was wired, it can be a real problem. A "regular" shop probably won't touch it since it does not fit into one of "their" books. And, electrical work can be very time consuming and expensive. So, not to scare you at all, just try to keep it simple. I've seen under the hood of installs by "professionals" and it was scary. Trying to figure out what someone else did can be "challenging".
hello,
so the RPM white signal wire feeds back to the old PCM? i follows that wire and it goes to the left towards oem PCM and not to the right under the booster wiring also the fuel pump you are bypassing the relay ?
The white wire that is by the "old" coil is your connection for the tach wire from your LS harness. If you have stripped away all your obs wiring, you'll have to do it another way. The fuel pump has a relay in the new ls harness fuse box that is made, so yes, you can bypass the old fuel pump relay...or have a 2nd.
@@laurencevillegarage the ls harness does have a tach wire and the obs harness still in place
I’m just trying to get the correct wires and label them and have them ready for when I drop the ls in with the harness and start tying wires together
So far I’m keeping the oil pressure sensor connector
The a/c connector
The temp sensor wire (3rd wire)
Starter wire
The grounds
Speed sensor wiring
I’ll need to look for the pink wire for 12v switch like you did
I might just be confusing my self a bit
I really appreciate your reply thank you
I'm struggling on 1995 k1500 ls swap trying to get speedo to work. Any help would be appreciated
I spliced the original vss wires with the LS vss wires that way both the speedo and pcm get the information. I’m sure there are other ways to do it, that’s just how I did it on that truck.
Where’d you get the ecm mounting bracket?
I used the factory bracket from my donor truck.
You have the factory fuel relay mounted on the firewall and a aftermarket fuel relay also?
In short, yes. Is it redundant? Yes. Is it needed? No. Does it hurt anything? No. At the time, I was following lt1swap wiring as a guide. Since I did not strip out any OBS wiring ahead of time, I now have 2 of each. I could (in the future) trace down all the wires from the OBS fuel system and delete them…but, with so many other projects to do with this truck, I probably won’t. But, when first installing the new motor and wiring, I did not want to begin cutting up wiring, until I knew everything worked properly. Otherwise, it might make it very difficult to track down wiring issues if it would not run. So, for now, the fuel system has a back up fuse and relay. Good eye by the way. Thanks for the question.
@@laurencevillegarage Good to know thanx again.
totally new to this and you lost me with the pink wire. So you cut it from the 2nd stub and connected it to the ls ECU? SO it is coming form the dashboard fuse box to the ECU?
There are a variety of "pink" wires that are "key on" power. It's up to you to decide which of them is the best to provide power to whatever you are needing "key on" power for. I highly recommend that since you are new to this to check out ebay for a GM C/K Pickup electrical diagnosis and wiring diagram manual for your year of truck. They are a fantastic resource for all wiring information about your truck. You will be able to see which wires might provide the best source of power depending on what you are doing. I'm sorry if this sounds vague, but every swap is different and a manual will make your life much easier. A sound investment. I have 88-95 manuals and the prices ranged from $18-35. As time goes by, I'm sure they will go up. Well worth the $.
Sir how did you wire the dual relay? For the pcm and fuel pump please
I have a longer video about the wiring and you can get all the info you need at lt1swap.com this is the information I used to wire it all up.
Where did you get your wire diagrams? I've tried the auto zone site and can't get it to work
If you will check out my video czcams.com/video/i3n-4bYoGbM/video.html it tells you how to find those schematics on Autozones website. The best schematics, however are the factory electrical and wiring diagnosis manuals put out by GM. Go to Ebay and search for your year of truck and the words "electrical and wiring diagnosis manual" and hopefully, there will be several to choose from and buy one there. I have from 1988-1995 manuals (you can search GMC as well), just be sure you are looking for the c1500 or c/k series. Best money you will spend for electrical help.
Are you in Lawrenceville Georgia
No, I’m in Sunset, Texas.
Been following both your obs builds. Great job! I'm installing a 4l80e behind my 04 5.3. Do you know if I can splice in my speedo gauge vss into the output speed sensor without any issues? Keep it up thanks!
I believe it will depend on your year of truck, for the '95 I spliced the vss wires from the tail-shaft plug together and it worked just fine. On the '91 I will know shortly as the truck has yet to be driven. I'll know for sure in a week or so and I can let you know the result.
Sorry forgot to mention the year! I am working on a 91 OBS with my son. We put an 04 5.3 and a 4l80e trans. Changed all the seals and swapped in a decent streetable cam. I will be using the stock oil psi sender as well as the 3 wire temp sender u discussed. The other question is about the volt meter. I have the 1 small gauge wire coming from the stock Alt. I assume that's for the volt gauge. Would I just hook the to the LS Alt? Thanks for your time again!
If I am understanding you correctly, in using the LS alternator, there is a wired plug that goes in the top that is in the LS harness AND there is the + power wire that attaches to the back/top of the alternator. I chose to run it the same was as the OBS alternator and run that power wire from the power control stub on the firewall directly to that mounting point. On the LS Suburban, that power wire comes off the + battery cable that mounts to the alternator bracket on the side. You can go either way, I chose to run it the OBS way because that was how it worked before with no issues.
Where did you put the obs starter wire to
To the purple wire off the LS harness block at starter,
Can I just put the obs purple starter wire to the starter or no?
How do I build a harness for a 98 Tahoe with a 6.0 and work on my factory gages
Not enough information and not enough room to even start in this space. You can always email me.
Send me your email address
Hello, I'm Kousuke from Japan.
I currently ride a 98, 5.7l VORTEC suburban.
I have a bad engine
I happened to have a 2003 Tahoe with a 5.3L l59 engine.
In order to install this 5.3l l59 in a suburban, do I use the l59's engine harness, PCM, and fuse box?
I'm not good at English and I think it's hard to understand, but I'm looking forward to working with you
Thank you for watching from Japan!! Yes, you will use the 5.3 engine harness, pcm and some parts from that fuse box. When you begin removing the 5.7, don't cut anything. Try to keep everything you remove (for now) and label things so you will still remember what things are if the swap takes longer than you plan for. Do you plan to keep the 5.3 stock or modify it? Finding someone to tune it will be very important. Check the information below the video for other ways to contact me that are easier to communicate.
thank you!
I sent it to the address you provided.
I need your help.
thank you,
@@user-qw7ou9un8j I have not seen anything. Send to Laurenceville Garage email.
Hey why are you using the old charcoal canister I’m trying to see or better word learn do i have to use mine thanks I was about to throw mines away
I wanted to keep mine to prevent unwanted fuel odors. I’ve seen others remove theirs, but never heard if they noticed a difference or just didn’t care. I am considering mounting mine under the cab on my next swap.
@@laurencevillegarage thank you so much for making this video and for the advice
How do u power up the cab
I suppose it depends on what you are starting with, but assuming you start with a running truck to begin with, you are only swapping out the engine harness. So, the cab has power as does the rest of the truck, it is only the engine harness you are modifying. That is why I tell folks to try not to cut or remove any of the existing wiring, remove the old engine, install the LS motor. Then lay out the LS harness the way you want it to lay in the engine bay. Thin out the LS harness of all the stuff you don't want or need. What you are left with is an engine with the sensors you do need and a handful of wires to integrate into your truck to make the gauges, fans, etc work. The motor only needs 3 wires to run. The rest is "optional" stuff. So, your "cab" should never lose power.
Hello sir, I hope all is well. I don't know if you'll even see this message, but I was wondering... did you use stock gauges?
Yes, I used all my stock gauges.
@laurencevillegarage thank you, boss 🍻
How do you know if your PCM is working
If it’s in a vehicle already, check engine light is on, engine may not start or if running it runs bad (misfiring or studdering), poor gas mileage, common codes would be P0600 and/or other codes in the 600 range. If it’s not in a vehicle, it will be difficult. You could remove from a vehicle and swap in another one to see if it performs the same way.
Just did a ls swap dbw but have no throttle response. P1125 code
Make sure tac module is grounded. Somehow one wasn’t. And no response. It gets its ground for the grey connector. Of of those wires.
Check your tac wires going to the pedal assembly and check to be sure no wires are pinched, cut or damaged. Did you re-splice the wires when you assembled? make sure all connections are good. Do you know for sure the pedal assembly worked properly prior to your swap?
I'm going to do a swap the donor is 08 Chevy express van I'm putting it in 94 Chevy truck and the ls is drive by wire and I'm bolt to 700r can I do a drive by cable
You can do it, but it will get a bit more involved. You will need to change your pcm to a PO1 unit that can do DBC, also, your current manifold has a 4bolt TB, you will need a 3bolt manifold or adapter…that’s not all… you can do it, but you might be better off sticking with the original intake manifold if you’re on a tight budget and keeping the drive by wire. You have other features on that 08 engine, that may require additional expense, like removing the DOD and VVT. If this is your first swap, try not to make it more complicated than it needs to be. It can get very confusing.
@@laurencevillegarage can you send me some start to finish points I've been following some videos but Im very new with all the l.s stuff I'm kinda old school
@@emmarichard1230 Emma, check out the information below the video and you’ll find an email address. That would be a lot easier to correspond with or other ways to reach me. Answering a lot of questions via CZcams is very difficult and limited.
Two questions. What are the part numbers for the 99 Camaro V8 Coolant temp sensor, and for the oil pressure adapter that you used to connect your OBS oil pressure sensor? I am deep into wiring up my 6.0 harness to my OBS 93 2500. Appreciate your videos. 🙂
temp sensor: www.ebay.com/itm/394526012660 you will need a 3 wire pigtail www.amazon.com/LS-3-Wire-Pigtail-Temperature-Connector/dp/B07HR26CV6 and I believe I used www.amazon.com/dp/B0894LDF76/?coliid=I2GJV1H3E5EP3J&colid=G0VZIDISO48J&ref_=lv_ov_lig_dp_it&th=1 it's been awhile... Good luck.
Super, I really appreciate your willingness to share your knowledge and experience.
@@gregjohnston1781 you’re welcome.