How to Wire LS SWAP OBD Connector + Check Engine Light - UTX

Today at Ugly Truck, we're wiring in an OBD2 plug and MIL light on our LS swapped 1970 C10. Whether you call it an ALDL, data link connector, or OBD port... it's pretty important! But the good news is, that it only takes 4 wires to make it all work!
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[@bdavis12758]

I know this is an older video but I always rewatch your videos. At night I play them, as well as some others so my ringing goes away😂 but I enjoy your knowledge base content and I use it to come up with my own ideas. I am building my plans for the LS in my 91 suburban with tbi so everything looks factory. I’d like to add a small turbo for some pep to get on the highway but not to build a race truck. I thought of starting my own small channel doing what you do as nobody really puts out the info and small details. I personally love small details bc they help build a bigger picture on my mind. Hope y’all had a good thanksgiving. Currently been at a school for work for the last 2 months and I miss my truck!

[@UglyTruckExperience]

Thanks Brian! We had a great Thanksgiving and hope you did too! Before you start thinking about turbos, check out our latest video! kzbin.info/www/bejne/eYjUaYKjqaZmgbM This is just a stock 5.3, and it's hard not to spin the tires. 🤣 But on the other hand, turbos sound cool, and "turbocharged" is a pretty fun word... 😁😁 We appreciate you watching our stuff!

[@bdavis12758]

@@UglyTruckExperience I have notifications set so watching your videos is not an issue. Lol. I just rewatch them. It’s my chilling time. My son watches them with me nuts he’s still learning. He doesn’t know enough curse words to build on his own yet

[@mrdaniel2071]

This information is priceless. Thanks for sharing. I can't wait to hook up my obd

[@UglyTruckExperience]

Hope it's helpful! We appreciate you watching! 👍

[@brianhaw9398]

Very convenient addition to a great truck!

[@UglyTruckExperience]

And we hope we never have to use it! 😁 Thanks for watching!

[@pjstartv6798]

I thought you were yanking our chain about the ODBII port having to be under the dash but I was wrong. Manufacturers are required to place the OBDII port within 3 feet of the driver and the port must be accessible without any tools. Over 40 years old and I'm still learning new things daily.

[@UglyTruckExperience]

I totally thought Jerry was kidding about that too... But then I Googled it! 😂 Thanks for watching!

[@brianhaw9398]

But if the vehicle didnt come with one you could put it anywhere convenient

[@Its_jaydee]

Haha heck yea I just did this 2 days ago but not with the bulb. Going to be adding that soon. Im swapping my 87 c10 a lot of tour videos have been a great help

[@UglyTruckExperience]

Awesome! Glad the videos have been helpful! We appreciate you watching!

[@GrandPitoVic]

Thank you. I was definitely trying to figure out the check engine light.

[@UglyTruckExperience]

Glad it helped you out! Thanks for watching!

[@DanielRodriguez-ty4qe]

Thanks for all your knowledge

[@UglyTruckExperience]

Thank you for watching!

[@gmray7301]

Another great video! Keep up the good work! I am taking a break and waiting on my buddy to do some work on the truck! See you guys!

[@UglyTruckExperience]

Thanks Ray! Your truck is coming right along! Those speakers and storage boxes turned out great! 👍

[@gmray7301]

@@UglyTruckExperience thanks

[@Elco_Trigga]

Just what I was looking for thanks

[@UglyTruckExperience]

Glad it helped you out! Thanks for watching!

[@brucedouglas613]

Good job video was a big help for me and my ls swap thanks !!!!! Dog lover here too.

[@UglyTruckExperience]

Thanks Bruce! We appreciate you tuning in! 🐶🐶

[@abrdds]

I confess... duct tape has made my check engine light turn off ( whistlin’)... and you are right about Roswell, ijs❤️... explanation was straight forward... you make this look too easy, wow...

[@UglyTruckExperience]

Duct tape fixes everything! 😁 We appreciate you watching, Anthony! 👋

[@franciskovaldovinos2409]

Great video

[@UglyTruckExperience]

Thanks Francisko! We appreciate you watching!

[@cesarzapata999]

Thanks for this information

[@UglyTruckExperience]

You're very welcome! Thanks for watching!

[@michaelcopeland4892]

Yes

[@betocano1987]

I like the ending. I'm a dog lover too. I also like old trucks with ls engines.

[@UglyTruckExperience]

Well, you're in the right place! 😁😁 Thanks for watching!

[@billthompson5634]

Nice drawing and video. I need to try the soldering BUTT connector. I over compensate my lack of electrical ability with buying really nice materials and tools to use

[@UglyTruckExperience]

Thanks Bill! I'm really excited about all my new markers. 😂 Those connectors are awesome! I think they're a lot easier to use than crimp connectors, especially in awkward spots like under the dash. Thanks for watching! --Emily

[@GMC6969]

Thank you very much for great video again! Some day i hope you can do a video on harvesting an LS and its harness from a donor truck. I Started taking one out from a 99 sierra got to fuse box and undid connectors. But the white connector wires mostly go into cab and not sure what to do. Thanks again

[@UglyTruckExperience]

Funny you should mention that... We have that exact video coming up very soon! It'll be a Tahoe, but it's all the same stuff. We have a couple more squarebody swaps coming up, so if there's anything else that would be helpful, let us know! Thanks for watching!

[@nanningying]

Thanks for your great videos. Do I need the original OBD 2 with many more wires to run Dakota gages with their BIM-1-2 or is the one DATA wire your showing do it? I want to get speed, oil pressure etc from the PCM.

[@UglyTruckExperience]

The Dakota dash will run off of this wiring. It just needs that one data wire at the OBD connector. Thanks for watching. Jerry and Emily

[@MiguelFlores-jp1ss]

Just found your channel and subscribed. Lots of great info. Your presentation is ez to follow and understand. I’ll search your channel for more. How about using both the engine and transmission (from a donor) and how to wire it up ??? Thanks for sharing your knowledge!!!

[@UglyTruckExperience]

Thank so much for subscribing! We like to use everything we can from the donor to keep our swaps simple and affordable... so all the swaps we've shown so far have the donor engine and trans, wiring harness, cooling system, etc. I put this together this playlist with all our LS swap videos if you want to check it out! kzbin.info/aero/PL3Xf8yWArPC5Zw2UPwTvSvFt8CjEBSFiO We appreciate you watching! 👋

[@MiguelFlores-jp1ss]

@@UglyTruckExperience Thanks for responding to my question!! I will definitely check out your video playlist!! GOD BLESS!!!

[@shadymaint1]

You mentioned the O2 sensors being different between your 4.8 and 5.3. I believe the difference is that the Canadian built trucks use a case grounded O2 and the US/Mexico built trucks are grounded by a wire. My 02 Silverado donor was Canadian built and has case grounded O2 sensors. It originally had a 4.8 in it. I swapped in a 5.3. Even use the 4.8 PCM to run the 5.3 with no problems at all. Im currently in the middle of swapping the 5.3/4l60e out of my Silverado into my 94 S10.

[@UglyTruckExperience]

That's interesting! Thanks for the info, Shady!

[@GrandPitoVic]

I love those butt connectors. I started using them and I haven't used any other type since. Thank you for the content.

[@UglyTruckExperience]

We're loving them too. They're pretty handy! 😁👍

[@protox07]

I like your videos

[@UglyTruckExperience]

Thanks protox07. I think you have great taste in videos. We really appreciate you watching.

[@RaysLaughsAndLyrics]

Well folks, better a Check Engine Light than👁️ a Check Engine Buzzer👂..Thanks for sharing.

[@UglyTruckExperience]

🤣🤣 This is true. Thanks for watching!

[@351cat]

Do you guys have a video of how you did the driver side battery mount? Im struggling with that part on my 68 right now.

[@UglyTruckExperience]

We do not have a video on that right now. On our 70 c10 we used the battery tray from a 2004 Tahoe and made some new brackets for it to sit on the driver side. Should probably do a video on that. Thanks. Jerry

[@stephenhasty7088]

Thank you

[@UglyTruckExperience]

Thanks for watching!

[@kennethprice9988]

Mil connection on 2001 Tahoe goes to inside fuse panel, please advise data wiring #58, and ecm ground # 46?

[@UglyTruckExperience]

Hello Kenneth. Your pin 58 at connector 1 at the ecm is the Data connection. Pin 46 on connector 2 at the ecm is the ground for the Malfunction Indicator light. The mil and the data connector are two different items. Are you needing info on both? Jerry

[@Joiscor2000]

God bless you.

[@UglyTruckExperience]

We appreciate you tuning in! Hope the video was helpful!

[@trailerparkcryptoking5213]

Thanks for showing these two things that I have been curious about! I have one more question, how is the neutral safety switch contended with? Thanks ugly trucks/cute camera girls!

[@UglyTruckExperience]

The neutral safety switch that is mounted on the side of the transmission needs to be used. That switch also lets the computer know that it is in gear or reverse. The original vehicles neutral safety can be left to work like normal or could be removed. That is something I will make sure to address in up and coming videos. I think she is pretty cute also. Thanks Jerry

[@trailerparkcryptoking5213]

@@UglyTruckExperience what would you do if you mated up to an old TH400?

[@UglyTruckExperience]

In that case you would need to wire into the cars original neutral safety switch which would be mounted on the steering column on a car or truck with shifter on the column.

[@MoTiiOnNz]

my 5.3 on a standalone harnes has a obd port but i can't get the scan tool to communicate after my engine overheated any tips ? i can rewire the obd port would that solve this issue? it was working fine before engine got hot

[@UglyTruckExperience]

Hello Oscar. The engine overheating would just be a coincidence I would imagine. I would start looking at the wiring going to the obd plug. Check it for power and ground and if all good there you must have a bad data connection. Make sure all the fuses that power the PCM are ok also. Jerry

[@jaxjax5322]

Does it work with a holley ? On a obs silverado?

[@UglyTruckExperience]

I know there are people out there that have done that. I have never done it myself. I do know that the OBS had some of the greatest SBC's in them for sure. If you end up doing it, let us know. Thanks for watching. Jerry and Emily

[@rrrobin2569]

Can you use the purple wire to run Bluetooth information for your dash? i.e. speedo, voltage, etc.?

[@UglyTruckExperience]

I think your probably asking about the data wire. If your using a aftermarket dash that uses a data connection to communicate to the pcm you could definitely use that wire. Some of them just plug directly into the OBD2 connector. Thanks Jerry

[@rrrobin2569]

@Ugly Truck Experience thank you Jerry. I'm am brand to LS swapping...lol. I love your videos, keep them coming. Can't wait for my 72 C10 to get on the road

[@chasevictoriano7266]

What battery tray did you use on this?

[@UglyTruckExperience]

I used the tray from the donor vehicle. 2004 Tahoe. Had to add some brackets to make it fit nicely.

[@PinkysHouse]

You said that it only has 3 wires, but mine has 3 wires plus the ground wires, there is a power wire, the data wire, and the two grounds wires but it also has a green wire(common wire?), and it has power going to it at the port so what is causing it not to work any ideas

[@UglyTruckExperience]

What engine and computer are you working with?

[@jannekallio5047]

Great video! Just what I needed :) I'm rebuilding my 72 Camaro dashboard. The previous owner swapped the angine, but did nothing to all the old cables and it is a mess. I already removed endless cables going nowhere. the fusebox looks horrible. All cables are wrong there. There is an OBD connector, but I did not manage to make the cheap readers to work. There is no check engine light as I think I managed to lose it when clearing all the useless cables away. I will use this video to continue working on it, but I think the first step would be so somehow identify if the OBD connector is even working ok and if it is, then check any alarms are on. If that is all ok, I try to indentify the check engine cable and test it turns on and off. Any tips you could give me? For example on those OBD readers. I don't want to get another that does not work.

[@UglyTruckExperience]

Hello Janne. 72 Camaro... Nice. We have a 75. I have some pretty cheap OBD readers around here and don't have much of a problem with getting them to make a connection. From the sounds of it you are picking up where somebody else left off and kind of left you a mess. The OBD connector really has very few wires that are required to get it going. You might be better off to get rid of what is there and start from scratch so you know it is correct. If I buy another OBD reader, I am going to purchase a Autel. They have one that is less than 40 bucks. I have some of their other readers and they work great. Keep us posted. Thanks for watching. Jerry and Emily

[@jannekallio5047]

@@UglyTruckExperience Thanks for the comment! You are right, I don't know why the previous owner did not remove all the old wires.. it would have been much easier while doing the swap.. it was a mess. Anyways, a friend of mine will borrow his reader and I will try that first. I have roughly 3 Months to rebuild the whole dashboard and I want to fix most of the wires during this time. My fellow old timer friends might hate me, but I am going full crazy with the dashboard, designing it in virtual reality and 3D-printing it in parts. End result should be quite wild. If I can pull it off, then follows other areas of the car. Some more practical and some just for the looks. Car already has so many updates that going for the original look does not make much sense..

[@UglyTruckExperience]

Hey Janne! That's awesome! Be sure to keep us updated and send us some pics if you can! facebook.com/uglytruck Thanks! --Emily and Jerry

[@markhoey]

Hello from Australia, just want to start by saying great video’s with good in depth explanations which can be hard to find when it comes to wiring, they have helped me a great deal with my Ls conversion, keep up the great content. One final thing I would like to make work in my swap is the power/economy switch (Ls1/4l60e). I guess all I really want to know is what the circuit requires? Am I applying 12v, giving it an earth or just breaking a circuit to swap between the 2 modes? Thanks in advance.

[@UglyTruckExperience]

Hello Mark. Let me know a bit more about what your donor motor and transmission came from and I will gladly take a look. Thanks. Jerry

[@markhoey]

@@UglyTruckExperience the donor was a 2004 VY SS Commodore. From factory they have a power/economy button which I believe all this does is allow the engine to rev a little further out before upshifting when in “power” mode. My wiring diagram shows blue connector pin 71 controls the function I’m just not sure what the circuit requires to switch between the 2 modes. Thanks.

[@UglyTruckExperience]

Hello Mark. I literally have no information available to us involving Holden's. It's sister car here in the US is a pontiac G8 from what I can figure out and I do not see this feature in it. If I had no info on that circuit, I would check for voltage when running. If it had very very little voltage, I would try grounding it. Do you happen to know how many wires wen't to the button on the donor? I wish I was more help and am curious to find out what happens. Thanks Jerry

[@markhoey]

@@UglyTruckExperience Hey Jerry, just wanted to let you know that grounding the circuit seems to work. It seems to be in “economy” when grounded and “power” when the circuit is open just incase you run into something similar in the future. Cheers.

[@UglyTruckExperience]

That is great. Glad to hear that it is working. I appreciate you fallowing up on it. Thanks Mark. Jerry

[@jeepdoctv]

How do you wire up the tcc to the brake switch in your conversions?

[@UglyTruckExperience]

We are actually working on that video today. What are you working on? Donor and swap vehicle.

[@jeepdoctv]

@@UglyTruckExperience my swap engine is a 2001 Lm7 from a 2001 Tahoe. It’s going in my scrambler.

[@UglyTruckExperience]

Ok This next video will fix you up.

[@jeepdoctv]

Can’t wait!!

[@eduardocarrasco8279]

Hi, i have a question i put an Ls 5.3(2001) in a 89 firebird trans am and i cant seem to get the check engine light right.I connected the light bulb wire one to the pcm wire like you and the other to 12v hot all the time and it stays on all the time when i open the switch? I would appreciate your help.

[@UglyTruckExperience]

What do you mean by? When I open the switch?

[@eduardocarrasco8279]

@@UglyTruckExperience when i open the switch the check engine light comes one and stays on all the time no codes though. Im putting new gauges so i wanted to put a bulb so i can see if anything goes wrong.

[@thebombperformancechannel9087]

Hey I copied your steps for the one 2 but I have no signal when I plug in my scanner

[@UglyTruckExperience]

What are you using for a donor motor, harness and ECM? Jerry

[@throttlewatch4614]

You install a check engine light just so you can put a piece of tape over it ?

[@UglyTruckExperience]

🤣🤣 Maybe I'll just mount it in the glove box... 😁

[@coconut_milk7167]

I can’t get my scanner to communicate with the ecu

[@UglyTruckExperience]

Give me some info on your donor and what wiring you have. Will take a look at diagram and see if I can help. Jerry

[@beasyphone]

Ok, dk green, yellow and purple on my blue ->OF BLUE/RED 1999 SSeries pcm are not giving me communication to dlc to pin 2 which is purple . (Pcm/dlc came together) pins 4+5 on dlc i grounded to brake pedal mount , pins 9+13 i just have cut and capped on dlc side as i think its airbag and sonething else unnecessary.. which pcm wire do i need to hijack to run straight to my DLC...thanks lol. Oh akso- double corneal transplants/ my vision is as good as night diving in new jersey..

[@UglyTruckExperience]

Pin 58 on connector 1 at the pcm. Blue connector. It is a dark green wire. I hope that answers your question. Let me know. Thanks Bret. Jerry

[@xdrenaline]

Anyone know if the gen 4 pcm have a mil port?

[@UglyTruckExperience]

A gen 4 engine has a mil light the same as gen 3. It uses a data signal. If you know what your donor motor and harness are from I might be able to let you know where that data wire is. Jerry

[@xdrenaline]

@@UglyTruckExperience 2007 corvette 6.0 donor

[@UglyTruckExperience]

Are you using the body control module on this swap also?

[@UglyTruckExperience]

I would guess that you are not using the BCM. You will need to find a Tan wire and a Tan with Black tracer wire at the ECM. The tan is in Connector 1, position 27. The Tan with Black is in position 28 right next to it. Those wires will go to the ALDL connector. Tan to position 14, Tan/Black to position 6. ALDL connector will also need battery power at position 16 and position 4 and 5 will need to be grounded. That will give a scan tool access to GM high speed LAN which you will need to look at ECM and TCM. The actual MIL light is grounded by pin 68 at the ECM at connector 1, it is a Brown wire with white tracer. Hope this helped. Thanks. Jerry

[@evlsc400]

@@UglyTruckExperience Came back here to say Thank You So Much for this information.

[@thabigghomie_]

💪🏾👍🏾

[@UglyTruckExperience]

😎👍

[@reditthome9130]

hello had a question about the check engine light video

[@UglyTruckExperience]

Sure, what's your question?

[@reditthome9130]

@@UglyTruckExperience im trying to run my own check engine light. got my wire in the slot 16 and ran my wire to the brown and white wire like you said but its constant grown bulb lit up with no key. i redesign my dash 2000 dodge dakota don't have my original gauge cluster. but in AZ i got to have a check engine light. i found 2 ground wires same color blk/TN 31 and 32 found a wire called "sensor ground" blk/LB 4 and a fuse ignition switch output wire lg/BK all read negative withe probe tool. so where would i run the negative wire from the bulb to the PCM to which wire because all these are constant ground?

[@reditthome9130]

4.7L

[@reditthome9130]

intellitronix 6 gauge i lost my seat belt light window washer light check engine light brake light abs light door ajar light cant find those wires but i do need the check engine light

[@UglyTruckExperience]

Are you saying your truck still has the original 4.7L in it? Is the dash the only thing you changed?

[@netster7601]

hello

[@UglyTruckExperience]

Hi Alonso! 👋👋