1996-00 OBS GMT400 Gen3 LS Swap Information

[@blackmanops3749]

Damn. I can't believe my luck. Just bought a Gen 3 LS 6.0 to put in my 97 OBS and was wondering how the heck I will wire the two together. I went to your channel and this was the first vid I clicked on. Questions Answered! You are the LS Wiring Maven for sure! And as far as wiring videos go, you are the Master! Thanks so much for your efforts. You deserve way more exposure than you get.

[@thegenrl]

It's good to see you are still in to it! Your website helped me 5 years ago swap a 93 LT1 in to my 90 GMT400. Still got it and it's a great truck! Thank you for sharing everything you do.

[@bummgarage9793]

So what I learned from this video is that I just need to pay you to merge my harnesses !!

[@MrFuchew]

of just but the holly terminator

[@jordantovar6855]

Lol right? I need my harness redone any recommendations?

[@Outofgasautomotive]

What wires in the ls harness do you hook the 20 wires that come from the 98 harness to ?

[@JoseContreras-mv5yz]

Lt1swap.com i say is the godfather who helped 1000s get started

[@jonasgrumby1093]

Thanks for all your support Brandon

[@Val-df7vk]

You're the man !!! Thank you very much for all this information on LS wiring swaps.

[@chrisford9637]

could you make a video of how you combined the harness with the connectors

[@MrGto05]

That’s where I’m stuck at too man! Any update??

[@franciscomarin6938]

That’s where I’m confused at now too 🤷‍♂️

[@CatsRuleXOXO]

I second this

[@chrisFamo]

Same here

[@haydenwalters8729]

Any luck

[@Jodah175]

Awesome video! Is there no way to use only the LS pcm to control the engine and abs? Say im swapping a 5.3 into a 98?

[@CapitalSpeedandSalvage]

I wish you made this video 3 years ago. but Thank you for the Information you help with for the LS swap enthusiast community.

[@haydenwalters8729]

Any detail on how to merge them? How to wire the plugs and how they plug into the ls harness

[@kathondonaldson9073]

Question? Might be dumb one but the factory obs computer or wiring is not needed at all unless you want the factory gauges to work?

[@chuntaritoslp88]

I’m in the process of trying to do a swap to my truck. Is this a service you provide? I’ve read almost all of the info you have on the website but just figured I ask if we can get this done by a pro?

[@FastPaull]

Man, thank god for the holley terminator x.

[@antoniosmith6703]

I know this an old video now, but my question is does this modified factory 5.7 harness get married to an unmolested 5.3 harness? Or, is it married to a stand-alone 5.3 harness?

[@chriswhite4596]

Awesome Video !!!!!! I have a 1996 Yukon 4wd that I plan on Converting to LS Engine someday

[@billyhodges518]

How did you tap into the wires on the neutral safety switch? Range signals from the 98 come from the firewall have to get mated with the range signals from the Ls computer?

[@SabrinaBarnes-e8q]

I know its been years since this was posted. I came across this video when trying to figure out something on my 1998 silverado. I dont know if you will remember at this point. I am hoping you might. At 24 seconds, you can see a brown wire with the white connector on the end of it. I have this on my truck and it is not connected to anything. This is the first time I have ever noticed it. I am wondering where it came disconnected from. I have searched and cannot find a spot for it to plug in. I have tested it and its live wire. I know it comes out of the bulkhead but I cannot find any info as to where it plugs in.

[@tom1994420]

By chance do you sell pre built harness like this ?

[@ManChildMaineiac]

There is a LSX Harness guy. Just like Brendan does programming. He does harnesses.

[@obsomar1148]

Did you ever find the part number to those connectors you used to merge both harnesses

[@smxz647]

He reused the oem ones he cut off

[@Aydolphgee]

does this info chnage if im using the ls stock fuse box? i had a running suburban removed everyhting and i have a running 1996 chvey silverado with a 5.7 i want to keep ac from the truck i already have the ict billet brackets for the ac the stay stock

[@Outofgasautomotive]

Ok so I want to do this to my 98 z71 4x4 but it's my DD and can't have it down for a long time so my question is can I get a harness out of a 2 wheel drive or does it have to be out of a 4x4 and does the ls harness have to come out of a 4x4 or can I use a 2 wheel drive harness and ecu

[@blairanthony3801]

I’m doing this right now. I’m blending the two harnesses. My plan is to keep the OBS PNP switch and connections. My question is, does my 2006 PCM need to have a signal from the PNP? Comparing the two wiring diagrams, the OBS range switch goes to the cluster and the 2006 Tahoe PNP goes to the PCM for logic. Thank you in advance.

[@obsant7214]

Does anyone know if theres just a plug n play harness for a 96 tahoe and putting in a 5.3 in it

[@andymac5324]

What brand brackets was used on this 98 for the stock ac compressor?

[@diduck6878]

Isn't that recirculation door pin repurposed for fan?

[@randalljames1]

thanks for the resource... Have you done anything to retain the "flex fuel" mode on these? doing a slightly hyped up build and would really like to retain the "Flex Fuel" sensor for boosted performance changes.. hitting something less than say E80 to turn the motor down?

[@douglasbeary7890]

Are you going to do any gen 4 stuff? Im confused about maf sensor Engine and hanes 2010 lc9 silverado

[@dalehall2993]

What about going from the 5.7 too an ls3?👀

[@locospeed01]

Do you have pin diagram for the c2 connector for a 99-02 truck

[@brianhess4777]

I’m doing a 96 c1500 with a 5.3 and a 96 4l60e transmission that came off the original 4.3 that was in the truck. I’ve got the 5.3 married to the 96 4l60e trans. Now I need to do the wiring, any info/help would surly be grateful. Will this work for my setup?

[@joatmon7621]

Brian Hess did you get this figured out? Currently in same situation

[@brianhess4777]

Jacob Snowden no I did not. I decided to go a different direction. I bought a truck that has a 5.7 in it and now I’m working on that. Good luck to you. I love LS engines, but their a pain in the ass when it comes to swapping them.

[@joatmon7621]

Brian Hess what year is the new truck?

[@brianhess4777]

Jacob Snowden it’s not new, it’s a 95 Chevy K1500 with an original GM 5.7 in it before GM sold the 5.7 blueprints to Toyota.

[@zxJC34xz]

Brian Hess sucks that you gave up on the swap man ! What all did you need to “marry” the 5.3 into the stock 4.3 4l60e tranny ? And what else do I need in general for the swap ? Obviously motor mounts, some new headers but what else

[@younggunn7907]

Hey I could really use some help finding a diagram of the under hood fuse box as far as what wire is for what exactly

[@LT1SWAPCOM]

going to have to buy a factory GM service manual. Those pinouts ARE NOT on electronic services such as alldata or mitchell on demand. If you pay attention taking apart the 98 harness, you can label the pink circuits and what you cut from the splices.

[@younggunn7907]

LT1SWAP.COM I really need to know which wires are for which fan and I think fuel pump and start

[@LT1SWAPCOM]

There are no fan wires in 1998 trucks unless you had a big block. The PCM pinout on my site shows where you can add a pin to the 98 pcm for 1 fan control. Use the PCM pinouts to locate the wire to the fuel pump. I talk about the starter wire in this video. It's the heavy gauge purple wire.

[@gerardolopez5875]

@@LT1SWAPCOM @@ how much the 2004 tahoe pcm , ?? Delete vats?

[@elianperformance5794]

Do you have a pin out of the big plug that bolts on top fire wall behind the fuse box under the brake booster to right a little ? I cut few extra wires and can’t find the temp gauge wire or volts or fuel level , I managed to find rpm and oil pressure, and I put the 2 vss wires together from 97 harness but can’t get gauge to read

[@keithw372]

would you ever sell this kind of moded harness?

[@JoseContreras-mv5yz]

I needed as well

[@chappyboylsx2596]

Do you do this for other people? I have a 96 c1500 4.3 2wd that i ls swapped, but I can not do wiring ..I have everything off body - motors, just need to find someone to do work that is legit..if you know someone or do this stuff let me know??

[@TheJoe1523]

Did you ever find somebody

[@zxJC34xz]

Mr Chappy bro what did you need for the swap ??? I’m currently trying to swap a 5.3 gen 3 into my 96 4.3 like you.. could you tell me what you need to replace or buy new for the swap to be able to be completed ?

[@ParkerJecks-ll5pb]

Is it a stand alone harness for the LS side?

[@lightningsurvivor1432]

Have you done any interior wiring? Stripping it out and redoing it?

[@snooterdavid1969]

Kno it's a old video but I'm looking for help trying to see if swapping a 2001 4.3 0411 ecm and harness over to 98 gmc sierra vortec 4.3 blackbox harness is possible. Need tuning options.

[@23steph13]

Hello. Do you know what harness i need to run a 6.0 ls and a 6l80 on a 92 obs?

[@scottcoleman284]

Very helpful info, thanks

[@hug00l]

I'm doing a swap on a 96 OBS chevy, can you use the original fuse block instead of adding one. The 96 has ENG and ECM 20A fuses for key hot. I was thinking of doing this: 20A ECM I : Injectors , PCM (original 96 setup) 20A ENG I : Coils, O2 sensors, MAF, TAC and I believe it has a dedicated Trans fuse coming from the under-dash fuse block. Fuel pump already has dedicated fuse and relay. Any input?

[@chevysleeper1]

Hello I’m swapping my 94 Silverado. I’m installing 2003 Tahoe drive by wire 5.3 but can’t find the pin out and how to merge the 94 to the 03 harness can you point me in the right direction

[@gabrielturner2365]

On the pwm fuel gauge output where dose that one go connected to the ls computer?

[@lit549]

on a 98 obs, does this apply the same if using a aftermarket harness and ecu? i cant find any info on that.

[@bigz_watts5476]

Do you have the pin out for a 1992 GMC Yukon

[@JerryVillarreal-mo3dm]

Ok I'm missing something here. Where do I hook up the obs wires to the ls pcm pins? I can't find the pin out info am I just missing it?

[@LT1SWAPCOM]

17:00 show the bundle that connects to the LS harness. The pinout linked in description on my website shows location on PCM.

[@panoramicview720]

Hi I've been reading from your online website. My project I have an 02' Tahoe 5.3L and I swapped a 04' 5.3L inside and converted the cable to electric pedal. I'm having issues with no start or anything. Am I missing something? The computer came out of an 05 Tahoe but rockauto has the 03' - 05' Tahoe 5.3L computers as interchangeable.

[@nathanwillis9196]

i have a c5 wiring harness and id like to keep the emission censors for smog. this is for a swap for a gmc sierra.

[@GLO1107]

How much for this integrated wiring harness???

[@andrewwalton477]

You need to do a 5.3 Gen 4 rewire video you would get a ton of views/likes.

[@calhouncalhoun2329]

How much would it Cost to get this done?

[@derrickfarrow5395]

Do you do wiring conversions for others?

[@jlvvlogs3204]

I have a 98 with a 4.3 want to put a5.3 do I still have to usr the original hardness or the one from the 5.3

[@plowmaster1206]

Is there a place to buy the harness?

[@jamest.5001]

Do you know if a 95 s15 is basically the same process as this? I'm thinking about swapping a 4.8L and 4L60 into the s15 4x4, thanks!

[@vandettabuilds6641]

Everyone has a printout for removing the wires on their swap I cant find the info for my 2007 chev 3500 LQ4 engine i have all the wiring since i had the donor truck Can you please help me????

[@kaisermora7012]

Would you be willing to adapt another 98 harness to an 04 5.3 harness? And if you would, what would you charge? Thanks.

[@LT1SWAPCOM]

no sorry...only did this one to document the process.

[@kaisermora7012]

LT1SWAP.COM Thanks for your response. Would you be willing to recommend someone? I tried it myself, but I'm lost.

[@Natehasrizz]

DID YOU GET YOUR HARNESS DONE YET ?

[@kaisermora7012]

ADAM ROHLFS Yes, I ended up doing what he did in this video. The only thing I haven't figured out is the AC and the fuel gauge. Using the 03+ green/blue pcm doesn't produce the correct signals. I'll probably end up putting the original pcm under the dash and wire it up for the AC and fuel gauge.

[@Natehasrizz]

Kaiser Mora I thought the gas gauge worked off the stock fuse block . Have any photos?

[@JeremiahIsreal144k]

So you just match what pin goes to both harness blue/red

[@poppajohns8072]

My 96 4.3/4L60e PCM has 5 connectors! I’m ready to start this swap but can’t find any info on the “5th” connector. It’s the smaller one that plugs into the middle of the ECM

[@hoghogwild]

You'll find that that connector runs to no where.

[@CatsRuleXOXO]

i got the same shit

[@madmikescustomDaily]

Love this video

[@poedaniel9954]

do you have the pinout for the passenger side of the firewall? also i have updated pdf harnesses in color if you'd like them, i'm putting a lm7 in my 97 4.3 truck and i'm having some wires from the passenger side of the firewall that i need to figure out where to run. i have a brown wire and the c100 connector has it labeled as fused ignition output type iii, is that just a key on power wire?

[@poedaniel9954]

i'm also trying to figure out oil pressure and coolant temp, other than that i'm done with my harness

[@poedaniel9954]

i'm now realizing i goofed and deleted the factory oil pressure wiring and now need to readd it 🙃

[@me13kone]

just did the 411 swap on my 2000 s10 everything good but my speedo dont work and wont shift gears, any help much appreciated. used a 2001 s10 411 pcm for my 2000 also using 01 motor.

[@peterstgo6620]

Friend, I remove my 4.3 from 96 gmc Sierra. Now I'm going with FiTech system (like holley), can you strip my harness in order to delete the un use stuff?

[@jacobgarci1023]

Will this work on a 93 Chevy Silverado

[@mexi409]

What would I need to do different for a 94?

[@lsx463]

Nothing difficult at all. Hundreds have worked with lt1swap.com to iron out the TBI GMT-400 wiring... bfy.tw/JRqW

[@johndelrio975]

Can you do this to an 8.1 vortec harness

[@dymonddable]

So nice and clean.

[@Sathalina]

will this video work for a 94 chevy 1500?

[@vxngarage3660]

No it wont.your truck should have a standalone trans module.theres some diffrences with 96+

[@23steph13]

Can I run a Ly6 with gen 4 harness and 58x crank, 4x cam, gen 3 intake/throttle body/heads, 6l80 Transmission?

[@LT1SWAPCOM]

no, gen4 ecm will require gen4 throttle body. dbw only.

[@23steph13]

Ok thanks. Can that be a blue/green ecm?

[@23steph13]

Yes definitely want dbw whether gen 3 or 4

[@LT1SWAPCOM]

@@23steph13 no. blue/green is gen3. If you have a gen4, you use gen 4 computer, gen4 harness, gen 4 throttle...so on.

[@23steph13]

Ok Ok. Gotcha. E38, E40. Thanks

[@kcwyrick7947]

How much do you charge

[@jerryrouse916]

Can I send you my harness and how much would it be

[@jays6.021]

Do you have a pin out fit 88-94

[@jacobgarci1023]

Have u find them

[@POPSIEsGARAGE]

Does anyone sell a ready-made harness for this?

[@abukawsar5357]

Hlw sir. Do have ss lumina 2004 5.7 all pcm diagram.

[@americanman911]

Hey man i just followed this but i have a harness from a 5.7 vortec, i have one more connector that i can’t seem to figure out what it is, anyway i can send you a personal message with a picture and maybe you can help me

[@americanman911]

Found out it’s for the water heater control valve, This would probably be a thing i should keep if i want my heat to work still?

[@joshsmock236]

Is this the same for a 96 I need this exact thing done on my 1996 no keeping abs keeping a/c and using the 96 neutral safety switch

[@artart7943]

96 and 97 passenger fire wall plugs are different. more of a square connector

[@edgarclemente5523]

need help for a 1995

[@Natehasrizz]

I would like to see a video or better photos of the way the plugs are hooked up! My tahoe does not have cruise control. any photos will help thank you THEOLDHOODLUM.....

[@Natehasrizz]

THE PLUGS FROM THE 98 HARNESS MERGED TO THE FIVE/THREE HARNESS

[@frankdatank7751]

That's why I went carbed$

[@codyyellott117]

Frank da Tank cause you are scared of wiring

[@pmotorsports8276]

You don't have to do it yourself. The $1500 you spent to go carburetor. You could have bought one aftermarket or paid someone to do it

[@hellpandart4133]

Can u send me a copy of that

[@LT1SWAPCOM]

copy of what?

[@hellpandart4133]

Sorry of the list to tap in to the 98 pcm

[@LT1SWAPCOM]

if you go to my website listed in the video description you will find the pinouts and other documents.

[@hellpandart4133]

Thk u I appreciate

[@Thetonygantjos]

Do you have documents to marry a 5.3 harness to a 93 harness or is the 98 the same? Thank you in advance

[@MrFuchew]

I would rather drive my 98 tahoe off a cliff than do this. This must be the most complicated way to achieve a ls swap

[@thelaughingman79]

oook so I think i decided to just stick a 350 in my 98 gmc serria. lol

[@chesterfield.mcdermott]

Hey! I'm struggling to find the PWM fuel gauge pin in the 0411 pinout, any hints as to what pin on that harness to either the blue or red? or where does it go if not into the ecu? Thanks!!

[@thomasguerrero4267]

What a/c set up does he is he says it from a 95 1500 but what bracket is used

[@HIGHPIPE5280]

I have a question so the neutral safety switch on the obs can I use the same 4 wires and connect em on the 5.3 ls neutral safety switch for the back up lamps and so forth?!

[@obsomar1148]

If you are using the ls trans, then you get the 4 wires and either cut or splice the ls trans neutral safety switch plug to the old ones

[@obsomar1148]

Or you could also make it easier if you have a 96-98 4l60e and use the old neutral safety switch