Ebay LS Swap harness overview with fuse ID, under dash wiring ID, and how to make this harness work!

** PLEASE READ DESCRIPTION FOR UPDATES **
** I have read online that moving the 5v and ground reference wires around is not necessary for this harness to work on a vortec engine. I have not tried it. Even if this is true I would STILL re-pin the harness to match your OS/PCM in case future troubleshooting is needed. If you ever have to troubleshoot a problem you WILL WANT those wires in the correct locations. Just because it may work does NOT mean it is correct. ** Video below explains this.
• Do you need to repin y...
What a mess! Are Ebay wiring harnesses junk? Are they made wrong? Why some many problems! In this video I go over a $99 Ebay red/blue 99-02 drive by cable / 4L60e stand alone wiring harness. If you are considering buying one of these you may want to watch this video. If you are doing an 03-07 gen 3 drive by wire engine swap please see my other video regarding that $99 harness.
03-07 classic GEN 3 DBW harness review video link below
• Ebay / Amazon LS Swap ...
03-07 classic GEN 3 DBW Fuse box wiring into the car and first start, wiring will be the same as this harness. Video link below
• Ebay LS swap harness i...
** There are a lot of harnesses on the market, your harness may not be the same as mine, or have the same design. Always go through every wire and compare your harness to what you need to have for your application **
** This harness was made by JY performance, so if you are looking for the same harness that I bought check the details on the eBay auction. This harness is sold by multiple sellers but will list JY Performance as the manufacturer **
First start of the 1955 Buick turbo 4.8 engine using this as modified harness video link below
• Ebay LS swap wiring ha...

[@RashawnDat1]

Just wanted to give an update. I bought this exact harness and followed your steps correctly but I wanted to add to your good information. The gray wire that's bundled with the fan 1 & fan 2 set of wires is actually the secondary wire to the alternator that goes into pin slot red 52. if you pull back the alternator loom you will see a gray wire taped off. You'll have to grab another alternator wire with the plug connection on it & solder it & put it in slot C. Thank you for this video and hope it helps anybody else wanting 2 wires for the vortec application

[@rust_hoarder_garage]

Good information, I will have to check my harness and see if it is the same. Even if the gray wire was not originally made to be used for the alternator the fact that the wire is already there means it can be used without having to run a new wire. I just bought another one of these harnesses for my 56 Chevy pickup build, so I will check it out on that upcoming video.

[@speedwolfusa2847]

This video is GOLD! Thanks for addressing the necessary changes. 👍👍

[@rust_hoarder_garage]

Glad it was helpful! Always check your harness against the factory pin outs to verify what changes you may need to make, regardless of the manufacturer.

[@amswrx]

Thank you I’ll be doing this before I install mine! I can see why so many people say they don’t work

[@rust_hoarder_garage]

check every wire on any low dollar harness just to confirm there wont be any issues.

[@jsbird98]

Thank you for this tutorial!! I repinned my JY harness exactly like what you showed here. Now my truck is shifting like factory again after the LS Swap. My 4l60e would get stuck in 2-3 and my tach wouldnt work. Now it all works. I do have to get new 02 sensors as my are reading .480ish mv so I need the case grounded o2's. But man am I happy. My swap has been done since july 23 but we couldnt figure out the trans/tach issue. Now to wire up my fans like you showed in another vid! Thank u 😎😎😎😎

[@rust_hoarder_garage]

That is awesome, great job and glad I could help!

[@darkgreen9098]

Just got here from Built on a Budget recommendation, new sub and thank you for this playlist I'm about to dig into.

[@rust_hoarder_garage]

Awesome, thank you!

[@russrocket2883]

So glad I found your video, i only had O2 sensor issues but after watching your video I found most of the same issues with my harness. The thing I dont understand is I actually got mine running and I thought it ran fine other than the O2 issues, really crazy. Thanks again.

[@rust_hoarder_garage]

The engine will run if the ground and power references are on the same buss, but the wires being in the wrong place will cause grief if you have problems and have to trace out the circuits. See my other video on why I re-pin these harnesses. Have fun with the build!

[@russrocket2883]

Got one other question on adding the wire on Pin 75, I believe you said to tie it into Pin 19 wire which I am assuming this is a ground signal for each bank of ignition modules. Am I correct?

[@rust_hoarder_garage]

no, blue 75 is a 12v pcm ignition feed wire, same as blue 19.

[@russrocket2883]

@@rust_hoarder_garage Gotcha, just don't how I got this thing to run without 75 wired in. I just happened to go drive it around before I started fixing the harness as you directed in video and when I pulled in the thing in driveway it shutoff on its own. Started it up again to pull it in garage and it run like crap. Hope placing wire in 75 and tieing it in fixes this issue that just popped up.

[@rust_hoarder_garage]

It all depends on what circuit on the pcm 75 is feeding, if you aren't using it then it would not be needed. I doubt it will fix something that was ok before.

[@teabag402]

Man these harnesses are jacked lol. Mine was wired all kinds of crazy. Once I learned how to check the pin outs and fix all the wiring issues it's great. Mine was a DBW, multec injectors and 1 wire map sensor 99-07 harness supposedly for Vortec 4.8, 5.3 and 6.0. "NEW For LS SWAPS DBW 4.8 5.3 6.0 1999-2006 LS1-4L60E Wiring Harness Stand Alone"

[@rust_hoarder_garage]

My $99 DBW harness I put on the 51 Hudson has been flawless out of the box, but I confirmed every wire ahead of time. I wouldn't use anyone's harness without confirming every wire.

[@moneymaker5052]

Amazing video… I had to do all the changes mentioned in this video…. Glad I found your channel

[@rust_hoarder_garage]

Awesome! Thank you!

[@SuperViper83]

Ha! Thanks for the video! Interesting thing I bought this harness for the LS1 (NOT a Vortec) engine which will be swapped into the my 48 Hudson. And when I bought it I even didn't know about those differencies. Also interesting fact is that they position this harness for the Vortec engine! At least this what I founded in the harness manual)

[@rust_hoarder_garage]

They list it as for a vortec, but is designed and laid out for the LS1, all LS1 type connectors and the MAF/IAT connectors are on the driver's side of the harness like an LS1. Good luck with the build, my 51 Hudson flies with just a stock 5.3!

[@SuperViper83]

@@rust_hoarder_garage thanks! Ye, I was lucky to buy a correct harness actually. Your videos like a kearning lessons for me :)

[@kq2799]

Best by far, harness video!!!!

[@rust_hoarder_garage]

Thanks!

[@rust_hoarder_garage]

*** UPDATE *** This harness is actually for a 4L80E transmission, which is why the brown TCC lockup wire was in the transmission connector "S" position and the white wire was taped off. Ignore that as being a problem with this harness, I ordered a 4L80e harness instead of the 4L60e by mistake. In the end the only manufacturer mistake was the tach wire being tied to 12v. All other changes needed are due to the LS1 / Vortec engine and operating system design differences. **

[@jsbird98]

I have two JY harnesses for the 4l60e transmission. One for and Ls Swapped obs and one for a 78 ls swapped T/A. Both have a 4l60e. So my question is, both tranny harnesses have the white wire taped back and the brown wire is in the S position. So I need to swap the white wire into S and the brown wire needs to go into U position for the 4l60e application, right? The OBS runs but will only shift 123 initially then promptly gets stuck in 3rd and can only manually downshift into second. I haven't swapped the wires in the tranny harness connector yet, I hope this fixes that shifting issue. Yes both JY harnesses needed to be repinned and the tach wire fixed(thank you for your videos!!!)

[@rust_hoarder_garage]

that is correct, the white wire should be in the S position for the 4L60e, that is the wire for the 3-2 shift solenoid, and the brown wire for the TCC PWM solenoid should be in the U position. This is how it should be for the 4L60e. Thanks for watching!

[@jsbird98]

Thank you for all your help. Your vids have helped a ton!!

[@Charlie_Foxtrot_]

You need more subscribers

[@rust_hoarder_garage]

It’s cool, I am doing this for fun, I think subscribers will come with time. Spread the word!

[@CharmleysChopShop]

😅You should just offer this service. Id rather buy an 80 dollar harness, ship it to you and pay you to do all this and be done. Also, what am I using to check to see if the o2's are working or not? Scan tool?

[@rust_hoarder_garage]

Problem is no time to do it, not enough hours in a day for the things I am already doing. As far as O2 sensors if you are using a 99-02 harness with black connectors and a 99-02 tune get sensors for a 2000 Z28, they will be case grounded with the matching black connector. Mine are working fine with this harness and can be verified with a scan tool.

[@Marksracingengines]

Actually... Awesome info brother! keep em coming...got my sub

[@rust_hoarder_garage]

Thank you! Lots more cool stuff on the way 👍

[@Marc_Wolfe]

I remember something about an extra white wire for use with the 4L80E. Not saying I know it wasn't an error.

[@rust_hoarder_garage]

This turned out to be an 80e harness, which is why the white wire was taped back, I forgot I ordered an 80e harness which is not what I usually get.

[@Marc_Wolfe]

I think mine had that too, and according to the LT1 swap info people swear by, the installed white wire was in the wrong spot. I also ordered a 4L80E harness, only because it was the cheapest. Got it as a starting point for using the ECU like a megasquirt. Just made and tested an LV3 sensor adapter.

[@Marc_Wolfe]

Yeah, same here. According to what I looked up, another wire was also pinned wrong.

[@Localmotivemedia]

Thank you very much for your time you have put in to this. Could you please post the part number you used for the o2 Sensors? I followed every step and used Bosch 13444 o2 and I’m stuck in Open loop. I can’t find any info on line which sensor is case grounded which blows my mind.

[@rust_hoarder_garage]

The Bosch 13444 should work, it is used on the 98-02 LS1 engines which is what the harness is wired for. I am using the same type sensors and they are working fine, I would have to see if I bought Bosch brand sensors. Have you scanned the car while running to see if the sensors are switching? Not going into closed loop can be from how the tune was done, engine not being hot enough, etc.

[@traypoll3350]

Thanks brother I just recently just brought a harness like that I’m about to do a ls swap in my 1998 Cheyenne most definitely got to check the Wires

[@rust_hoarder_garage]

Smart move, check them all and compare them to the wiring pinout that matches the engine and PCM you are using.

[@babybird57]

I have a '94 Cheyenne and am considering a ls swap, how did yours go?

[@6xcchamber971]

Thank you so much!!!! Huge resource....

[@rust_hoarder_garage]

Glad it was helpful!

[@shadymaint1]

For the amount of work it takes to get this harness to work correctly you might as well rework a factory harness.

[@rust_hoarder_garage]

I can do it either way, but not everyone can.

[@AlCurtis-g9s]

tHey Thanks for the great video and the advice on the oxygen sensors. So I'm getting ready to FINALLY fire this baby up, but I'm having an issue. I have 12volts coming into both the ignition relay and the fuel pump relay on crank and key on( spliced it just before the relays as you suggested. But only the ignition relay is clicking on- no fuel pump- i crossed the connections on the pump relay and the fuel pump came on- I've tested the relay, so I can only guess the computer is not sending instructions to energize thefuel pump relay (its a green wire).might be a longshot but I'm Hoping you might have some idea what might be going on.

[@rust_hoarder_garage]

Check out my video on the 1951 Hudson first start, it goes over the fuel pump relay wiring, I am not sure how you have it wired.

[@AlCurtis-g9s]

Thanks-i just watched the section from that video as you suggested- I had spliced into the power wire that feeds the ignition relay- so the same wire basically feeds the two relays, do you think that is my problem?- i saw you ended up running two seperate circuits. Perhaps i should try that- I assume both relays need 12 volts on key and cranking.

[@rust_hoarder_garage]

There are two wires you need to add to the fuel pump relay. Full time 12v to pin 30 on the relay, and the wire to the positive side of the fuel pump from pin 87 on the relay. The green wire to the relay should have 12v on it from the PCM for 3 seconds unless the engine starts, then it will stay on 12v. Black wire on the relay is tied into the ground wire on the harness that is in the under dash bundle. There are two ground wires in the harness I used, one goes to the back of the drives side head and the other goes to the dash or somewhere metal inside the car. So verify the green wire goes to 12v when you turn on the ignition, verify the black wire is grounded, verify you have 12v at all times on pin 30. If you have all of that the relay should turn on and send 12v to pin 87.

[@AlCurtis-g9s]

wow amazing video- my harness is pinned the same as yours- went through your fixes- my harness came with quite a bit of info- including compatible parts/sensors- they list my oxygen sensors as delco afs123. these seem to be for a camaro- do i use these to match my harness or get ones called for the vortec?

[@rust_hoarder_garage]

The harness is made to use case grounded O2 sensors, so I would use the 2002 Z28 O2 sensors. They should have black square connectors and are case grounded. I am using the same style with this harness in my 55 Buick turbo LS build and they look to be working fine. Thanks for watching and hope it was helpful.

[@suppathowed]

Awesome content ! Just got an lq4 with a ls1 dbc intake. I belive i wound need ls1 dbc 4l60e harness . Using the f body ecu. It should be plug n play since im NOT using a truck ecu, right ?

[@rust_hoarder_garage]

Should be but I would still verify every wire position and check the tach wire for being tied to 12v.

[@suppathowed]

Thankyou very much Sir

[@Kloco78]

Do you have a link for the video where you wire up the fuel pump?

[@rust_hoarder_garage]

Turbo 55 Buick that uses this harness has a video for wiring dual fuel pumps with a separate relay box. 51 Hudson uses a similar harness and there is a video in the play list on how to wire the fuel pump using the harness relay.

[@cityking8951]

My question is …If I put a 5.3 vortec pickup engine in my Firebird & change all the stuff that’s needed to fit f-body (like alternator,power steering ,water pump ,brackets etc.) What wire harness should I get ?

[@rust_hoarder_garage]

If it were me and I had a factory LS1 car with a blown engine and swapped in a 5.3 long block I would use the LS1 tune, retune for the 5.3, and leave the harness LS1 based. If I were building a hybrid with mismatched parts then I would wire it to whatever way matched my base tune, F body or truck.

[@cityking8951]

@@rust_hoarder_garage I’m swapping my stock v6 engine for the 5.3 truck motor . Do u think a stock Ls f body wire harness will work after making interchanges to the parts on truck motor

[@rust_hoarder_garage]

If you are using an LS1 tune to match the LS1 hardware you are putting on the engine I would leave the harness pinned for the LS1. If you are putting a truck PCM on an LS1 engine with all LS1 parts I would load an LS1 tune. Just how I would do it, up to you how you do it.

[@melerojose22]

My harness had an extra loose wire on the in cab bundle an extra white and grey. What would they be for?

[@rust_hoarder_garage]

I can only tell you the wires that came on my harness, and those colors seem to be standard among many harnesses. White is normally the tach signal and gray is normally one of the F body only non used wires.

[@CharmleysChopShop]

The only issue ive run into so far is the 1 wire alternator exciter plug is getting 5 volts with the key off. No clue why.

[@rust_hoarder_garage]

unfortunately I can't help with that, I would trace back the wire and make sure it is not tied into any other wires and is going to the correct PCM pin.

[@CharmleysChopShop]

@rust_hoarder_garage actually after following your steps for the white tac wire at pin 10 on red, it fixed it. They must be tied in somehow. Thank you!

[@rust_hoarder_garage]

Excellent! Nice job and thanks for the update.

[@CharmleysChopShop]

I've run into the issue with blue 79 now. First test drive out it was throwing a p0785 code for 3-2 shift solenoid. I'm going to see if mine is the same and follow your steps

[@br6ndonjones]

Its the tach wire back feeding

[@jonathanvargas4290]

Wouldnt u just be able to tune ur PCM for ls1 instead of vortec

[@rust_hoarder_garage]

LS1 used different flow rate injectors, different MAF sensor with different table values, etc. Truck hardware should use truck software.

[@kindrickhuncho9107]

What did you do for MAF connection for the 02 vortec if it’s the 5pin

[@rust_hoarder_garage]

As I said in the video this harness is being used on a turbo car in speed density mode, no MAF being used. If you want to use this harness with the truck MAF you will need to buy or get a 5 pin connector and splice in the MAF and IAT wires.

[@nandojayy7183]

Do you have a link to The Harness you bought?

[@rust_hoarder_garage]

No, but this one is made by JY Performance, I would use this one. They are for sale on ebay under a few different vendors.

[@2ballcureall]

So can you use this harness as is with a 5.3 and flash the truck computer to a 99-01 fbody computer?

[@rust_hoarder_garage]

I think you are missing the point of re-pinning, the computers are the same, but you want the pinouts to match whatever program you are using so that everything matches. Otherwise if you have a problem the schematics will not match what you have for future troubleshooting. If I am using a truck program I want my wiring to match the truck schematics. If I am using an LS1 program I want the harness to match the LS1 prints. That is how I do it, what you do is up to you. See my other video on why I re-pin for more information. Using this harness as is with a truck program is like wiring your living room lights to the kitchen lights circuit breaker. It is functional but wrong.

[@EricAtkinsonMusic]

I have this same harness ..I have a 99 fbody that was a V6 and I put a 5.3 LM7 in it but changed everything to LS1 ..my intake is LS6 with a DBC throttle body .. do I need to repin this harness sir ..I would appreciate it if you could help me out here .. thanks 🙏🏼

[@EricAtkinsonMusic]

Also I have another question I think my last one was answered in someone else’s text..but the 3 plugs on the firebird fender by the shock tower do I just look those up and splice them into this harness ?

[@masonbedell9540]

So if I'm dealing with a reference grounded o2 sensor I gotta add a wire from the one that runs to the pcm and pin it to b 63?

[@rust_hoarder_garage]

Ignoring the secondary O2s the schematic for case grounded shows the primary bank 1 O2 sensor low side wire to blue 29 and bank 2 primary low side to blue 26. For the reference grounded O2s the low side wires are tied together and then go to the same blue 29 and blue 26, plus an additional wire to blue 63. So if you are running reference grounded O2s the low sides should be tied together and the additional wire added. I just checked my case grounded O2s and they are working with this harness as I wired it on the video.

[@russrocket2883]

How can you find out if you have case ground or reference ground sensors? I just found your video and both O2 sensors are not working and their is no pin on 63.

[@anrtard9452]

How the flip are you not a top KZbin

[@rust_hoarder_garage]

Thanks, maybe over time? I am doing this for fun so I appreciate anyone who wants to subscribe and follow along.

[@PeteDacurse]

What about an orange wire mine there with the pin and everything do u know what that orange wire for and would I need it? The one going to the transmission

[@rust_hoarder_garage]

I do not know what harness you have, for transmission pinouts you will need to compare what you have to a 1996 or newer 4L60e connector pinout diagram. You need to trace each wire from the PCM to the transmission connector. Color does not matter, only that each wire is in the correct position.

[@PeteDacurse]

@@rust_hoarder_garage I have the $85 one u did the video of but on mine a orange wire was not hooked up to the transmission plug 🔌 I already checked everything u should on the video I’m just having trouble finding what that orange 🍊 wire is for

[@rust_hoarder_garage]

where does the orange wire connect at the PCM, which color connector and what pin number?

[@PeteDacurse]

@@rust_hoarder_garage is on the red color pcm bundle of wires but is not hooked up to it and the other end is on the transmission connection but not hooked up to

[@PeteDacurse]

What I just find is that it might be for ATF TEmp should be a yellow/orange wire going to pcm red connector #51 and I do have a yellow wire on #51

[@antalamo]

Hey, I’ve been binging on these vids especially your LS swaps on both 50’s models. I have a quick question on the Jag front ends and wanted to know if there’s a way to reach you….email, Facebook, messenger? It would help me out if you can answer a few questions. Thanks

[@rust_hoarder_garage]

Best to post a question on the related video.