In this video I have a look at a customers 2008 GMC Yukon Denali with the big 6.2 that has a stalling issue. The vehicle will run for a little while, then it quits and will no longer talk to the scan tool or start!
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Hey folks, we got us a GMC it's the denial version. it is the 2008 variety. It's got the big 6.2 liter and it did run until I pulled it in and apparently that's the issue the fellas have and you drive the vehicle sometime for a certain period of time until it warms up he says and then it just it quits. The gauges go funky, a bunch of Lights start flashing and that just that's it.

leaves you walking so that's where we I started up I let it warm up outside I think I got scan tool. all that stuff right then no sooner I brought it in. go grab a scan tool. scan tool won't communicate and then that was it.

It stalled and then it won't restart. Nothing clicked, doesn't do anything. So I left it sitting here for a while, a little, probably an hour or so I had some other stuff to do see if it. yeah, still a no start and then I'll show you what I noticed right off the bat.

of course it wouldn't Auto ID but when I did the full system scan on it to make the observation that everything here on the high speed Network So it's your engine control module, training control module, brake control module, body fuel pump, trailer, brake. Um, what is this one? yeah, electronic suspension control. None of those communicate. so something has pulled down or you know there's a module one funky or something that has messed up the entire high-speed data bus.

Now everything here on the low speed Network all functions and talk to it, but it talks to it on a different pin I think that's pin one on a GM I Could be wrong, but I Think what we need to do is find out what module is going to put on this thing and dropping down the whole network. So not a big network. network guy, not big diagnostic Network guy We don't see a lot of these issues at least in my shot. so we're going to do some basic checks we're going to check to see.

Network Integrity You know we're going to do a resistance check right at the daily link connector. I've been six and fourteen and we should see 60 ohms if it's perfectly intact. There's two 120 ohms resistors I think one in the engine module and I think it has one just separate in the back and with that being said I need to get a diagram for it so we know what the heck we're looking at. We can identify these modules if the network seems intact.

Uh, with lack of of knowledge and experience in this I think the best way to attack it. my Approach is to split the system down as much as we can and see if we unhook the back half or we unhook a bunch of modules. you know what's the easiest way to do this. Does the network come back to life and the other thing we can do after we check resistance is see what the data Network looks like where our voltages look like.

Does it indicate you know something funky? Some kind of funky funky I Don't think that we're dealing with a bad ground. uh, or you know, power supply or anything like that just because we lose the entire Data Network And if we just say for example, if the ECM had the background or was missing power or something to the best of my knowledge, it doesn't take out the entire network. so we're going to take our Dvom, You guys can see that right there. We took our leads.
They're good. I left the key off for a little bit I've got an old Bob here. Whoa. Oh good catch fella.

Um, we're gonna go on pin 6 and 14 because it's gonna be our high speed. Network We want to see we're looking for 60 Ohms Wow. I'll be dip. Look at that.

we're at 109. 109.7 I Don't think real stations go that high. Uh, technically we should have the battery and hook to do this, but there is no network activity on here right now because otherwise she'd be blinking. so that's kind of interesting.

That's uh, tells us we have some corruption going on here. I say we're pretty close to 120. so that's pretty interesting. All right.

We'll keep that right in the old back pocket. and then I think the other thing we can do while we're right here. let me plug the scan tool back in plug that back in. let's turn our key on keys on and I see right now that we don't I used to have pin 6 and 14, they were blinking on here.

Yeah, we're still a no start. so let's take our scan tool here and we're going to back out. We're gonna come out of here because we can actually check our data bus here. Whoops! If I can get to the right data pit here, go to measurements then we're going to go to bus inspection.

look for our goodness for you. There's no glare on here for you. so let's see. we want to be our waveform and we can see.

Okay, let's slow this baby way down. We'll go 500 milliseconds per revision and we can see I'm Can High. It's sitting steady around. Oh never mind There She Goes I see that just started flashing I Just heard something click I wonder if it'll start now? Wow.

Lucky, lucky, all right fixed just like that. Fix it right in front of your eyes. So anyhow, I thought I heard something clicking in there. but let's look at this while it's not broke.

what we're expecting to see on Can High is a two and a half to three and a half volt. uh communication line here Square wave however you want to say it so we're going to take, we're going to put trigger on here. We're just using this because it's handy and uh, so it's super fast as you can see. Quick.

like a little money. Let's go 200 microseconds per division. That's probably a little too fast for us. Um, this way here we can see our data communication.

We can stop and have a look, but these taller spikes I think are denote like end of transmission. You know we're not going to get into that whole deal because really, it's kind of not important right now. But what is important is we see these data packets being transferred at I Think approximately the correct voltages. So that one there.

Where are we at? here? We're at um, you know, two and a half to about three and a half volts. Now we should see just the opposite of this on Can Low. It should be a mirror image reflecting this. We have to move our trigger and remove our trigger and we're about two and a half to one and a half volts here.
Let's skip this back here a little bit. We'll get some. Got some mumbo jumbo going on here though. It's not near as clean, but it could be breaking down on us right now.

So yeah, we're well. about 2.2 volts to about 1.2 volts ish. So we're just going to take a look. We just kind of want to have an overview so it's Can Low.

Let me get rid of our trigger. It's Can High Can low. Unfortunately with this, we can't look at them both at the same time. It is interesting I Thought it started out about two and a half volts.

Let's see, there's two and a half volts right there. Oops. Oh, when I get rid of that, it goes away. That stands the reason.

So there are lines at two and a half volts. Go can high and I can't high sitting on Two and a Half volts. I Can low is a little different. Um, is that something to be concerned with I Don't know.

But what I do want to know now is we're going to shut this back off. I'm gonna wait for it to quit talking here. We're gonna plug our scan tool, but now that kind of works. I'm gonna wait for pin 6 and 14 to quit deerber.

Jabber Always important if you do any network testing. Unplug your scan tool. all right so they're done talking. now.

let's just see what our resistance value is. Now we know it was close to 120. it was like 110. So we're gonna go six 14.

and we are at of that so it's shorted right together. It says it's at five. Ohms interesting. but it was still talking right 6 and 14.

truck still runs. Does it like I said. We should have the battery on hooked for this test. but nope.

So the truck's dead right now. It doesn't start again, However, it's communicating. Put this back in so that's pretty interesting. But now as I plug it back in.

now look at our can low. it is shorted because that's a can high. Now we're going from zero. Yeah, this is all screwed up Now now it's definitely broke.

I'm hearing something clicking inside the dash again I don't know if that means it's coming back alive or I Can low essentially is just reflecting what we have on Can I Accepted starting out at zero volts. so there is definitely something going wonky here. Without a doubt Dash is going crazy. Okay, our Network went from 110 ohms to 5 ohms just while you guys are sitting here watching this.

so there's definitely something going or going astray because you 've. seen this and what's Curious I guess I'm just going to think out loud here while I got you guys right here. I haven't looked in this vehicle obviously. So I don't know what's wrong with it.

What's Curious is what seemed to change. it is just leaving the key on. it's not so much and this was my thought too when I first talked to this guy. Is this thing breaking down because it's getting hot? You know physically from you know from heat running the engine transmission's getting hot or is it getting hot, key on, engine off, or can engine running just Electronics getting hot? You know? Could I push this thing in and just left the key on and we could have seen the same issue.
I don't know I Think we're going to go down our same path. We figured out a couple things: I Do still believe that we have a module that's going haywire? Let's get a diagram, find out where we can break the system down and start looking at it from there. So that's the diagram. They're actually two diagrams.

This diagram has all the low speed Network on it. So this is. uh, let's see. Here's our data link connector right here and I was right.

Pin one is the the GM low speed so that comes out goes to this comb and then feeds everything over here on the low speed which we're not concerned about, feeds everything over here on the low speed. All that stuff works so we don't care about that. But what we're looking at is pin 6 and Pin 14. They come out all the way up over here and then over there and onto page two and that's the high speed data bus.

Now what we need to do is figure out and I'm just making a big fat assumption here is that there's a module going wonky. What I would like to know and what I don't know is can we just remove power from the module and restore our Network Because I don't know that I'm going to proceed with this method. So Pin 6 and 14. they come over here and they come down into this junction box which is pull that away so I can read it below left end of Dash I Don't think it's going to be much use getting that, but here's something that we can know.

it goes to that these wires are tagged together and they go over here to the body control module, goes in, then back out, comes down to the transmission control module, goes in, back out goes to the engine control module and then that's the end of the line over here. the other spot it comes in, the jumper is over goes to the Bcim so it's gonna be for your OnStar it goes down here, back in and out of that junction box again goes to the transfer case shift module um assuming it has it yet with Auto 4x4 without all four by four. So if it has it um you know it goes to the Transportation Control mod or transfer case goes to the electronic brake control module in and out and then from there it goes to the external resistor and then with four wheel hydraulic power brake without foil Hydrox power brake and then uh okay so there's a couple discrepancies here, where it could go to and from and then the fuel pump flow control module and then the electronic suspension control module. So what we need to do is what can we unplug because these you know comes in and out.
What can we unplug and eliminate most of the system and then we don't necessarily even need it to run. So let's say for example, if we can get to the body module, we unplug the body module that takes out the transmission that takes out the engine control module and that's it. Takes out those ones well. plus the volume, six up body module, inch control, and um, transmission.

So let's see where the body module is. We got to start somewhere and at least we can eliminate and we can. What we can do at that point is look at our our data bus that we were looking at. we're expecting to see.

you know the two and a half to three and a half volts on the high speed uncorrupted? You know, clean signals, low speed two and a half to one and a half volts. Uh, you know, nice nice signal. Um, if we unplug this and the Signal's still crappy, well we know it's not this, this or this and then we can glide this half and start eliminating it down. That's the only way.

I Know how to do this. Um, let's see where the body module lives. I Think that's easy to get to and the other one I Think it might be easy to get to on this half I Think is this transfer case? uh, shift control module. Assuming this vehicle has it, it's a 6.2 It might not.

We might have to look and see if it does if it, does. I Think that's right under the dash. That's easy to get to also. So let's find.

let's find these little guys and see if we can learn some. Of course, let's verify it's still broken. All right. I Think we can all agree it's still broken because it's going from zero to three and a half on can high.

Yeah. I can't load was super screwed up. Okay, so it's still broke. Body Control module: I Want to make sure they're on the same connector? So Tan Black and Tan.

So Pin 16 17. nine and eight are both on connector X3 So let me find that. so I got that unplugged a little different. still broke.

Granted, we would have removed the resistor from it, it wouldn't look like this. Um, definitely still even receiving some crop message here and it's still broken Now let's uh, just review our thoughts here real quick. So I guess we could check a couple things. So this is kind of nice on this diagram like I say we have an external 120 Ohm resistor here at the back of the chassis and then the other one is inside the ECM So technically here, let me Shut the key off technically with this connector unplugged.

So we disconnected this connector so these two wires are open. We should be able to go down here on pin whatever that is I can't read it. Nine Eight I guess and we should have. If this side of the Network's intact, you know 120 ohms over here and that like I say I think by unplugging this, we eliminated the we eliminated the engine control module and we also eliminated the body module.

I Believe all three of these are not our culprit in theory. If we check at our data link connector now, the only resistor we should be able to see is this one unless it's still shorted or there's some kind of funny business here, which we know there's funny business. There is something going on. Wound again here.
Let's see in a perfect world, we'd have 120, but we know something's broke. Okay, so we're at 120. which is correct. Very interesting.

Okay, that was 120 ohms right now I didn't look at the uh, it was like 120 kilo ohms or anything. right? Okay, 120.4 So that shows that Network being intact there. Let me plug that one back in, plug the body module back in and see if we're at 60 now. So that's kind of curious.

We're not. We're at 14 on 6 and 14 with the body module plucked back in. I Think this is the red herring. Um, I know I should follow my facts, but that's part of the fact.

It's easy enough for me to unplug this body module. I'm gonna plug that again I Want to make sure that we have 60 ohms coming this way or 120 ohms coming this way to the engine controller? Against my better judgment. I I'm going to do it just just because. um, standby.

let's see if I got the right ones. Yes sir. Okay, third, try that boy. You guys were the first couple tries I couldn't see because I didn't have my readers on.

let's see. So I think we're pin eight and nine which is black. They should be right next to each other. tan and then tan with black.

there's a tan. Yeah, it should be. Let's unplug this. So we're not getting any erroneous readings here.

so it is number I Got little numbers on here 19 to 25. so let's so if that's 19, that's 18, 17 and 16. Was that an option on here? It is 16 and 17. is an option and that's that.

Okay, all right, so we're good. So 16 and 17. is the network going away from the away from the engine computer? So that's third. There's that one here and this one here.

We should see 120 because we've already checked this half of it. 121 Point Whatever. Ohms, if you guys can see that. So now we need to check the other half.

This is the half that runs towards the engine computer. I'll stop it, you jerk And that is the third one. Third row down. Third is one end, Third for a second, Third row down, third, this one.

and this one. This is the one we were getting. the funky the Funky Monkey readings on once we plugged it back in. We should see 120 here also.

And we do. But for some reason when we put them together and they go through the body module, we don't see 60. there's that one and there's that one. Theoretically, if I hook these together, let me go get a jumper standby see I Thought of some kind of red herring I was chasing here.

So we take these and go like this. We'll go 10 to 10 and totally bypass the body control module here. That one Tanner Taylor black I can't see I don't want to jump for the wrong one. so tan with blacks on the inside.
Okay, which is black? This one's black. So if we jumper this one here and we jump for this one, yeah, our Network should be complete. and then when we check it here with old Bobby come here. Bobby Here's our boy.

Bobby Now we got to get some other test leads for our voltmeter. We'll get these now. Theoretically, we should see 60. Ohms what happens when we plug it into my module? Let's see.

So there's our old meter I want pin 6 and 14. there's six. There's 14. I should see 60.

because 120 plus 120 is 60. Okay, so we know. Wiring wise, our network is 100 intact. We know that.

so let's unplug that now. Now we got massive cables down here. Let's get this out of the way. So I'm sorry to drag you guys through the mud here with this whole thing.

but I'm gonna plug this back in. You know what we should have done and what we're going to do before we get too far here. I Get my glasses back on. We should turn the key on with the buy module Network Bypassed see what it looked like? Okay, so let's see this pin and then the other red one that we're gonna go right above it and then the black.

We're gonna go right beside it. Let it being about it. boom. I Don't think our body modules are culprit, but let's just make sure we're back at 60 6 and 14.

we're back at 60. Ohms. we're gonna plug our scan tool in. Boom! We're gonna turn the key on which I had to take it out because the tag was hanging down and if you guys see somebody's name you go freaking crazy.

So we had to take that off keys back on and then we're going to look at the network. failed to start. Scope check BCI Connection Oh I gotta wait for the mic PCI to get back. Connected Standby: Okay, it's still broken.

Okay, oops, let me sneak past you here so it's still broke. That's can high, that's can low it's it's still busted. So it was a red herring but if I didn't if I didn't check it, you guys wouldn't believe me. There's all kinds of trust issues pulling the plug on that.

We pull the plug on it. there's less chatter, but the fact of the matter is, it's still broke. So let's just make a quick note of what we know. We know it is not the body module that's causing a problem.

It's not a training module. It's not the engine module. We know that because when we unplugged it here, we eliminated that. That and that.

we eliminated those three modules. so we got it narrowed down. I did not see a transfer case control module when I had my head under there top. half of my head's still there.

So we need to break this thing down on Star module. Yeah, it's got OnStar but that lives behind that mess so we're not getting there easy. So we have ABS module. We can unplug it easy and that's going to eliminate.

You know these three guys I Doubt you know it has anything to do with our resistor. We know that's good. We've already checked it. My suspicion is right here.
The price of Gambling Man my name was Kenny I Just like this guy. How come? because I've seen these stupid things catching on fire in my shop and it's always a suspension module. but I'm trying not to just take a swag as they call it a scientific wild that. Guess? um but I think at this point we need to just get it up in the air and see, is the brake control module easy to unplug.

Is this thing a giant green plus sack at the back of the car like they always are? Or is this a giant green plus sack at the back of the car like they always are? So let's uh, let's do that. Let's get up in the air. So this little guy, the ABS module hangs right out there. Fuel pump control module hangs right there and we come in the back.

and I think if I get you guys in frame where you at and hits that's the connector right behind that wiring harness for the suspension control module which lives above the spare tire which it looks that looks like a posh sandwich starting in there. So I'm sure that's probably gonna be our problem. Um, 90 of these. General Motors Air suspension doesn't work anyways.

this one has already been eliminated. Air hoses are hanging right there, the pump is, uh, well gone. so this one doesn't even work. Anyways, yeah, somebody's already cut the wires for the rear shock, so looks like she, uh, she left the show a long time ago.

The guy did say this is just this junker. it's just a winter beater. Um, so let's just try this. Let's just do something for the sake of testing here because there's a high probability that I am wrong and my guess.

So let's keep with our scientific approach if you will. Where we're breaking the system down, let's look to see. Let's get the scope working again here. I Just heard it beep up there I Just want to see if it's still broke and it is.

So there's our high speed Network We're still all the way down to zero volts and bouncing all the way up to, you know, three and a half gear. And you know that though that is not a data transmission. Okay, so we're gonna hit play on that. and being that the ABS is right here and easily accessible, let's eliminate this which is going to eliminate the fuel pump.

It's going to eliminate the suspension module. It's going to eliminate the rear resistor. What? I'm thinking it should also clean up our waveform is my guess. It's a good thing I'm a guesser because looks like we just fixed it.

Boys Can Low. There we go. Can low. Let me get this back to where.

Oops! I'll reset this thing. There we go, we're back at zero so now we can see. Can low goes from Two and a Half volts. Of course it's gonna be a little noisy because we're missing a resistor on the circuit now, but it's going from two and a half down to one and a half shimo.

Like I said, it's gonna be a little noisy and a little messy, but for the most part we can see I Hope you guys can see. Let me get this back to two two and a half volts which is right, Yeah right there. 2.51 So two and a half to one and a half. let's hit play and then our can high should go from Two and a half to three and a half and so it's can high can low and that's with this unplugged.
So that means the problem is either in the fuel pump control module or the rear suspension module right? So our our thought process worked foreign connector comes over I don't know you guys can see. Hopefully we eliminated this half and then we come down. We're going through the OnStar module right now. uh the answer module.

We don't have a transfer case module so it bypasses it and we came down here to the brake module so we know it's not the bcim it's not transfer case shift module and it possibly is a failed brake module which I doubt or a failed fuel pump module or a failed suspension module. Easiest thing to do now if you want to keep checking this process. we plug this back in and unplug this. That will tell us if our problem is in the brake module.

So I hope you guys follow along here. My Ethereum practice on this may be complete garbage, but it works for me, so now we can see it's broke. This module is easy enough to get a hold of. make sure to unplug relatively easy think wait, let's unplug it I Want to break this over here? Oh, there we go.

So there's that. Let me. uh, hang this back up. Okay, with this unplugged, our network is restored yet again.

can high, can't low. So that tells us that the brake control module is good because now the Network's running through everything through the brake module and we just broke the circuit here and now it's fixed so that eliminates eliminates it down to it's either the fuel pump control module or the suspension module. If we wanted to know for a fact, we could stick a set of jumper wires in here just like we did on the body module. We jumper the network in to the out and the into the out.

On the on the plus and the minus side and then if it's still broken, we know that this module is good in the module at the suspension bad. but I'm not gonna do that because I'm a gambler and I highly doubt that this is bad. Um, just because it's not solid pus. but the suspension module is.

So what we need to do now is go back to the suspension module and unhook it and then bypass it. jumper it so we have our our 60 ohm chassis resistor is back there somewhere. This this resistor lives back there, you know, probably taped to the harness because the thing we could actually do. Yeah, let's go back to that connector.

I'll see if I can get it I doubt I Doubt the spare tire will come out of this thing without being cut out with a torch, but we might have to do what we got to do. I Don't really have a good place to put you folks, so I'm going to try to I'm going to try to reach up and grab. Oh, grab the connector. How about we just grab the whole module.
Um, that's super duper handy that it's broken because the fuel filter X right in the way. um I Think right? I can't freaking see. Oh yeah boy, you're my baby. I got a good eye in there.

Um, okay. there we go. Boy oh boy. what? You're lucky.

look at what up? Let's uh. I'm gonna keep you guys in the crappy position that you're in. kind of yank this down I Want to get the connector unplugged while? I'm right here? Yeah, possibly yes, baby. All right these unplugged boys.

There's mama you guys can see, but she is. Holy Holy Holy Sorry about the crappy footage here, but we're pretty fortunate though that there was nothing holding this thing on. and look see, she's rusted through. Um, however, it is not finished.

but it works. Look at that. Okay, so there's low speed, there's her, high speed and oh, and so we can go like this. Now we should be able to talk to everything even though the, um, even though the resistor is out of the circuit, it should still.

Oh, look at that automatically. Id'd it, so that's good. We can go to Auto ID now before it wouldn't I had to type in the bin manually and now we're working on a Yukon I'm going to ask some some questions. we've got automatic HVAC We gotta wait for the OK button to highlight here.

It takes a minute. okay and then we should be able to do a system scan. We should see everything on the high speed now. of course it's going to have codes in it because well, because we were fiddling and because it's missing.

It's part of the network so it's good. it communicates now I don't really care about the codes. We need to finish our job back here. Okay, let's get a little bit Huggy here.

To finish the job, we need to find our Network wires which is going to be tan and then tan with black and they should all be pretty close to each other. Um, there's a tan. This whole thing's young so it doesn't matter, that's tan Tama black. They're usually right close to each other, which okay, so we're gonna guess there's that a tan.

There's a Tama black. We want them out of the harness because we need to continue on with the loop here. There are some other tan wires in here, but they're Tan White usually Network wires are right next to each other. We can check them with a scope.

Also, there's tan, tan, black and then inside here. Or we could just short them together. see if it takes the network down, there's a tan. there's a tan black.

Okay, so those should be in a perfect world. Our Network wires could be wrong. I think I'm right and then what we need to do. This is super awkward.

sitting over the top of you looking into your ear. Got freaks. Let's see, we're going to take I Do need to move here because you're making it super weird, right? It's not as bad. it's just going to drop a bunch of crap in the lens now.
But that's okay. we're going to take those two and we're gonna take these two and we're going to hook them together and stick this whole thing in a bag because there's other wires on here I Think most of it won't make a difference. Chances are the fuses are you've been yanked out of it. Would be my assumption being that everything else has been disabled and uh, we're gonna put these together.

so he's got a 60 Ohm resistor. In the very end, Theoretically, we could take a 60 Ohm resistor and just put it across the two Network wires coming in, which that's a that's a possible option or we could just hook it. We could just hook it back together, which we'll do because frankly, who's got a 60 Ohm resistor kicking around? I Mean we do. but we're not going to waste it on this truck.

so let's just strip these wires back. Oh man, we're making things go. being in there, we probably should turn the key off I Don't think it really matters. Okay, there we go.

So let's see. So theoretically painted black, it's a tan in Black Let's see, we do it. We didn't have some wire nuts on. boys twist these together.

That should clean up our pattern a little bit and it should give us 100 60 the ones I'm at 60 I'm taking away your cover from that one. We should have 60 Ohms now at the Daily Link connector. where these Twisted together in theory right where we sort of have. we should.

Actually, if we measure it right here, we only have to let the car down, but the keys on so it might not be right. But let me look at the waveform now so everything looks functional There weekend here, the car should run all right so it runs through our Park shut the key off down here on Bible Let's unhook that and then let's wait for the network to go down here. I'm not going to unhook the battery. we might have to, but that could have been screwing up our results the first time.

Okay, 6 and 14 are done blinking so the network is let's see before, but we should have the battery unhapped. Okay I guess number 14. there's number six. We're looking for 60.

and there we go. 60 doing some change. so that's really good. So we've got our wires correct back there.

good guess on those and that's it. The car is fixed easy baby. We know we've got the right wires and every one of these, well it's gonna drop sock around my arm I Can feel that. oh I'm scared of it.

That one you get around here right? there's that one. Let's make sure I got that other one. You have to worry about getting tired on me there. We go there, we go there we go.

Another look together. Good. Let me get some heat shrink now. So I have to get some bigger.

Oh no, there we go. Fits over nice and tight. all right. Shove right down on that wire.

Oops, it's all right down over that one. so there's two pieces of heat shrink. Cover those up all right. There are many torch here I Just want to make sure you shrink the end so they go right.
Shut hand up here. Come nice and hot. give them a little pinch with your fingers, sassy adhesive in it. Well, that's higher in a Banshee Who would have thought, huh and then we'll heat shrink them down on this end.

All right. they're shrunk down nicely and just be sure that end is sealed. Good I'm gonna come just about a quarter inch up from where we did it. Cut them.

Oh yeah, the old adhesive is oozing right out of that baby. See him on this end. Cut that. get one more pinch so make sure the water is not going to get in there.

Okay, that's good. So those are good and sealed up now like I say I think we'll um we'll just cover up this whole connector with a bag and a zip tie to keep the dirt and salt. This truck don't have much longer left in it. Another year or so it's gonna be in the scrap yard.

The way to fix this properly. Let's say you're doing this and and the and the cause of the problem wasn't corrosion, but it's just you know. bad module. um or let's say you had a functioning air suspension.

The way to do it would be to buy a new air suspension module, put it in, program it and you would be done in this case. Like I said the truck is junk so we're just treating it like junk there. What? We're never there. We got us a roll 33.

Watch this. you guys are gonna freak out. But but here's the other way that we can do this. We just got it.

It may not even matter. I there's there's a Serial date a wake-up line in here which I Don't know if it's just independent but we're just gonna go like this because we don't want to find out. I'm not going to do a whole lot of time into this thing. If we can keep this thing from turning into a giant green puss sack for a year or two, then great.

We've been covered off with tape. The other thing we could do too is we could just plug it back in. That would keep it from getting crappy. We're just going to go like this.

This will seal it. Awful. Scotch is pretty good. Come back around this end.

Stick that. Just like that. we'll go around there some more. This guy that people freaking out in the comment section at this point.

That's right. I already spoke with this guy so we're cool Man, we're all on the same page as far as me and this dude. I'm gonna come around this side. this is a back.

Wood sticks right here. Folks bypassed me a lot of GM Data networks. We're pretty familiar with this repair. Um, however, I Will admit I am not the guy to watch for Network Diagnostics is my weak point I Do hope to get better at it someday.

but I don't see a lot of beta network issues. However, I'm usually able to track them down relatively easily just using common sense an analytical thought process. Let me finish wrapping this up. You guys gotta move.
You're making it too weird. so we'll finish scanning here. I See, we have a just one coat now in the body control module which I don't know. You would think I would think that there would be a module that sets a code against the suspension module, but maybe nobody has to look at it because nobody cares what it's doing.

So buying model has a code in it here. Lots of time with vehicle. Dynamic control module so that's interesting. It's not suspension module.

the Dynamics is uh, like the yard and stuff right? like I think it's in the steering angle sensor. maybe? so that's interesting. That's the only. uh, only a little guy that's not talking of course.

I don't know how many codes were in this thing. you know prior to it coming in. we'd have to give the customer, but I'm quite surprised to see the other modules on the high speed Network aren't tattletailing on on this guy saying like, hey, we can't talk to this fella but evidently they don't care otherwise they would flag a code against it. So that's it.

We're done. chills over foreign folks. Uh, pretty easy one on this one. It's an older vehicle, not a lot of modules.

There was only, or at least on the high speed. there was only how many here. One, two, three, four, five six. It was only six.

So uh, which is pretty easy because by today's standard, that's really not much. The low speed side had, uh, what? Two Four, Six, Eight, 10, 12, 14, 16 like 18 modules on the low speed side, which that's also pretty easy to diagnose because they've got a junction box that you can go to in assuming you can get to it and you diagnose them a little bit differently. Now, as I mentioned, I'm not a super strong uh Network guy the majority of them that I fix are these old junk GMS you know and I've seen everything from bad, you know, so fuel pump modules taking them down uh I've had some late models come in with OnStar vehicle uh, communication interface module taking them down, body modules, ecms, you know, you name it. these things have a host of problems.

So why you know if I wasn't doing a video where I started data link connector being honest with you seeing the car, seeing it's all rotted out, probably not I probably wouldn't run right right for the gut still. I would have went back there visual inspection on this guy seeing if you could shake the salt out of it just because I see that more often not and I've actually had these I had a Cadillac in the shop once this actually caught fire in the shop, had it on the alignment rack up in smoke. It goes. Car was an absolute piece of crap.

It was like an 09 Escalade rotted right to pieces and I could smell it and she started sizzling and uh, unfortunately or fortunate I was able to get it all unplugged and you know Jumper in park the piece of crap outside so he could take it home. She didn't want to put any money into it and uh I shoved a couple paper clips in it so she could get it out of here and that was it. However, I did start the data link connector this time because I wanted to bring you down just a regular thought process if I didn't know anything about this car or pattern failures on. General Motors how would I start this problem and that's how I would start at the data link connector.
and just like when we're trying to find a short in a wire or yeah, I guess we'd be looking for a short where we, you know we got something spilling the fuse. We're gonna break the system now. Help we cut this thing in half and say, you know this half's good, This half's bad. Break it in half again, break it in half again.

You know you start out this big part of the funnel and you're trying to get down to this little pinpoint part of it. Does it work on every network configuration? No, it doesn't. Does it work on every? Network Style No, it doesn't on this one. A super simple, You know, data networks like this.

It's the easiest and fastest way to do it. Even certain there weren't doing a video, we don't have much time into it getting some measurements, but again, you know I've seen that red herring of the resistance values changing and I didn't really want to get into that, but we checked it anyways. So I hope it's useful to somebody. I think we've done some other networking problems like on Chryslers I think we did a carry van once that was pulling down the whole interior can bus they had a wire chain through that was pretty interesting, but the same same process like you know, where is it, where's the issue coming from and uh, the reason I don't know a lot about them is because I don't see a lot of these faults outside of, you know General Motors Um, unless it's a module that's completely dead and just you know, dropped off the network.

that's totally different. We see a lot of that on all different kinds of makes and models, but actually having something take out the entire Data Network I Just don't see it a lot. collision shops see it, and typically if we see it, it's corrosion or if somebody's been there. Typically it's not just a fault that happens at random, at least from what I've seen.

Usually ninety percent of time somebody's had their fingers in there things. Been in a collision body shop did a crappy job putting together, you know, black taped up the harness. You know somebody's been there. something to touch.

Anyways, go on there, touch that keyboard and uh type on it with fingers. Find us on the NC The Facebook. You guys know what to do and just my viewers. If I can do it, you can do it.

Thanks for watching.

99 thoughts on “Gmc yukon denali: no start, no communications”
  1. Avataaar/Circle Created with python_avatars 77 Zrod says:

    Good Ole super 33+!!!!

  2. Avataaar/Circle Created with python_avatars Raymond Horvatin says:

    looks like a proper deactivation to me two thumbs up thanks for sharing

  3. Avataaar/Circle Created with python_avatars TommyMacDaddy1 says:

    I'm a Chevy guy. It boggles my mind that these modules are under the vehicle exposed to spray, salt, vermin, etc. I wonder if the enginerds leave their laptops outside in the snow and rain. How stupid!!!

  4. Avataaar/Circle Created with python_avatars Wieddo I'nepro says:

    What exactly makes this a "winter beater", and headed for the scrap heap? It has the desirable L92, and as a Denali, comes loaded, including AWD and the G80 locker.

  5. Avataaar/Circle Created with python_avatars ramp yxl says:

    i really enjoyed that and looking forward to more like this from SMA, I also live in the rust belt but in Canada ontario

  6. Avataaar/Circle Created with python_avatars David Cornell says:

    I love how you show what's wrong and how to diagnosed the problem and fixed it…even though you already kinda knew what was wrong… very educational on how it works… love your videos, keep them coming…

  7. Avataaar/Circle Created with python_avatars Arpeggi says:

    Love the troubleshooting videos

  8. Avataaar/Circle Created with python_avatars Esmar Salazar says:

    You know you could have just bridge from the connector , right ?
    No wire cutting!

  9. Avataaar/Circle Created with python_avatars Mark Hollins says:

  10. Avataaar/Circle Created with python_avatars Gargamel Gargamel says:

    As a non- certified tech but with some schooling and some ocd, what do you think about some silicone before the heat shrink?

  11. Avataaar/Circle Created with python_avatars Danny Cole says:

    I've eliminated the air suspension on just about every GM suspension that comes up with problems. I have a few contracts with used car dealerships at a little lower labor rate. You know how fun auction cars are. Man the things I've found. A 2021 chevy equinox. Loaded with all kinds of issues. Well, they had welded two cars together from the B-pillar back. That said; the used car dealerships always want it eliminated. I keep resistors in stock at all times.

  12. Avataaar/Circle Created with python_avatars John Bragg says:

    Cracks me up when you say, trust issues. ha!

  13. Avataaar/Circle Created with python_avatars ricky johnson says:

    Great video. I use a very similar process but I don’t have that fancy breakout box I gotta get me one of those.

  14. Avataaar/Circle Created with python_avatars william hall says:

    usually don't mind the every day diagnostics, but without diagnostic training and 100,000 in tools, this one was a bit hard to follow for this family man backyard-er with his test light, meter and fix all hammer.

  15. Avataaar/Circle Created with python_avatars Michael Hill says:

    Great diag you're the best. Man I hope Rainman ray not listening

  16. Avataaar/Circle Created with python_avatars Sean Ramirez says:

    I know that people absolutely hate Common Core Math. But it teaches you Eric's thought process. It's not about the math. It's about the problem solving process.

  17. Avataaar/Circle Created with python_avatars interstate odd jobs says:

    Come on man Electrical Tape? you should use Duct tape! Just Kidding! Job well done.

  18. Avataaar/Circle Created with python_avatars Mohamed Ahmed says:

    Your electric tape wrapping skills are on bar with doctor's bandage wrapping skills, you're like a surgeon with that thing.

  19. Avataaar/Circle Created with python_avatars Fred Walker says:

    It’s elementary my dear Watson! Love it, like closing a bus stop, hook the light bulb wires together & the bus still goes by ! LOL👍

  20. Avataaar/Circle Created with python_avatars Willie Yarbrough says:

    thanks for the videos

  21. Avataaar/Circle Created with python_avatars 69malibu496 Stroker says:

    Excellent video! Love watching your process and thinking it through out loud.

  22. Avataaar/Circle Created with python_avatars Mike Cee says:

    It's hard to believe that a vehicle that new is that rotted out. Once again I'm glad that I live in the south-down here there are a lot of examples of that age that look new underneath.

  23. Avataaar/Circle Created with python_avatars PB Maine says:

    Its important not to fight the electronics. If you go at it logically it can be your friend (?).

  24. Avataaar/Circle Created with python_avatars Gera Grabovich says:

    Great video Eric I love it. I love the process. I love the result. The one thing I don’t love is rust and I’m glad I don’t have to deal with it anymore.

  25. Avataaar/Circle Created with python_avatars Robert La Cob says:

    A tough job made to order for Eric O, showing his computer skills again. A good synopsis of how you broke it down for us instead of using gut instinct from experience. Don't know if I would ever own a GM product again as I see everything new seems to be junk these days. Very poor engineering and design. Thanks Eric for the enlightenment!

  26. Avataaar/Circle Created with python_avatars james showacre says:

    Got a little rare ASMR Eric O around 36 min was almost peaceful lol

  27. Avataaar/Circle Created with python_avatars jtoddk98 says:

    The underside doesn’t look too horrible for a 2008, But not great. One of the added expenses of living up north, don’t expect your vehicle to live very long

  28. Avataaar/Circle Created with python_avatars Sarge Freedom says:

    CAN can be a real problem. We had them on generator systems .
    Great troubleshooting, diagnosis.

  29. Avataaar/Circle Created with python_avatars Bruce MacDonald says:

    Company called Mouser electronics that could sell you a box of 120 ohm resistors if it would help in diagnostics.

  30. Avataaar/Circle Created with python_avatars John Murphy says:

    Under the subject of Salt belt diagnostics,no one can compete!!

  31. Avataaar/Circle Created with python_avatars Electromecani K Autodiagnóstico Avanzado says:


  32. Avataaar/Circle Created with python_avatars gerald seely says:

    Good stuff

  33. Avataaar/Circle Created with python_avatars Bert Grau says:

    That's interesting, I didn't realize you could by pass a module, and the car still run, or in this case, help it run .

  34. Avataaar/Circle Created with python_avatars Idiot Savant says:

    I’ve been telling guys. It ain’t going to be the government banning ICE or these trucks rotting apart that will be the demise, it’s the freaking electronics.

    If you’ve ever taken the engine bay fuse box apart, it’s just a circuit board with pins for fuse, the coating and face lift off the board and you’ll suddenly get a bunch of codes for list of systems that are in reality all working properly. And at a GM dealer shop, they’ll just replace all the sensors and parts at your expense until they figure out its the fuse box… which is now on back order for the past 12 months. And the trucks a boat anchor without that fuse box.

    So if you own these 07-13 GM trucks, expect to be scrapping them in the next 10 years.

  35. Avataaar/Circle Created with python_avatars Keith Libner says:

    I love when the hot plastic melts to your finger, interesting looking blister.

  36. Avataaar/Circle Created with python_avatars Railnut says:

    GMC =

  37. Avataaar/Circle Created with python_avatars Dennis Gundlach says:

    excellent video eric, i was not bored at all.

  38. Avataaar/Circle Created with python_avatars Jason Campbell says:

    Anyone else think having 50 control modules in a vehicle where most of them are exposed to corrosion is kinda stupid !!!

  39. Avataaar/Circle Created with python_avatars George Bell says:


  40. Avataaar/Circle Created with python_avatars Roxanne Abbott says:

    Could you have used an infrared camera to see what module is getting hot? I'm still learning here.

  41. Avataaar/Circle Created with python_avatars sepresley1 says:

    eric your the man…super smart