Let's see what we got in the Chevy lineup today. We got the 2019 Chevrolet It's a Z71 What is a 19. supposedly it's a North start keeping fobs in it. got towed in Chevy How many miles around this thing? It does not start 34 000.

nothing's happening. Neutral: Oh, look at that. Would you look at that started in park? No start, no start. I am pushing the button.

Neutral: Is this thing under warranty? foreign? He's got it here. So let's just find out what's wrong with it and we'll find out if maybe it is under warranty. I would think it would be 19 is kind of new. Make sure it's not a coincidence here folks.

Yeah, no it's not a coincidence. However, the park neutral safety businesses it's goofing up. Must be a mechanical switch. Now it's not working.

Yeah, it starts to neutral every time. so definitely we're definitely on the right Trail here. Yeah, it's definitely broke, bro. Don't know if we actually need it, but it gives us kind of a brief overview of the entire starting system.

or at least most of it Anyways, there's a couple things that we know and uh, one thing that I really want to look at, it's going to be this transmission internal mode switch. Now it just shows one here on this diagram sending a signal on the edge of control module. And of course there's Communications back and forth. Uh, for the power moding to the body module, back to the PCM And then ultimately PCM is going to send our signal out and uh, you know, hit the starter.

That's kind of a real brief explanation. I Wrote down a couple of the RPO codes that this thing has as quickly the eight speed and the start stop system. I Don't know if any of its role of it, but I jotted it down. Main reason we want to look at that switch input is because we know when we tried to start it that it wasn't starting in park and we tried that a couple times and it failed every time.

Uh, what's weird is up on the dash, it shows it being in park. Okay, but it's not weird at the same time because modern cars oftentimes will have you know several levels of redundancy build into them with their switches. You know, for example, might have a switch and uh, you know, in the shift housing and one in the transmission. and you're maybe a couple in transmission or two different ones on the uh, you know, column housing or something like that.

You know, not this vehicle particularly. but you know other vehicles that we see, uh, like this that you know don't want to start and park but it still says park on the dash You know one, you know somebody might think it should have a park neutral switch in the transmission and then broadcast that over the whole network so everybody knows where it's in. You would think that would be the case, but it's not always the case. I Don't know about this one particular.

I'm assuming that's not the case because it says park on the dash so something sending a park signal. but it's not the same park signal that allows it to start and park. Obviously because it doesn't I threw a battery maintainer on it. Um.

I got the key on I've got the scan tool over there firing up. We're gonna first start with scan data. We can probably identify the problem just looking in there. As my assumption, we know that the starter is good, the battery is good, the wiring is good though.

you know the ground's good. The relays are good. the fuses are good because it starts in neutral. All right, let's see 2019.

Chevy She is red hot. That's a pretty sweet color. Uh, we're gonna go into uh, the GDs here. Let me make sure this thing still doesn't start.

Nope, it still doesn't start. so that's good. Uh, let's see I don't use this tool every day. so I'm going to be a little bit fumbly on it just throwing that out there.

We are going to go to vehicle diagnostics because we just want to see. you know, is there any code stored in any of the modules that is relevant to our problem? All right, let's see here. so there are no codes. All we have is a whole bunch of green check marks over there on the left.

so we have no codes so that's good and kind of surprising. Not surprising that we don't have a code for this problem, but just kind of surprising that it has no codes at all. Typically these will have a code for something. So let's go to system Diagnostics And then let's hit the back arrow because we screwed up and let's go to module Diagnostics.

Let's see, let's um, go to transmission. I'm going to guess we'll find that transmission control module I might have to poke around here for a while. There's a lot of modules on this vehicle. We're going to go to Data and then let's see.

Well, we're gonna go. So we got torque converter shift, solenoid valve clutch learn says we're going to go right into transmission data I Think might be the best spot and let's see what we have for switches. Oops here's this guy getting a click happy. Okay, so we have internal mode switch shows Park Transmission range shows Park And then we have the Abcps switch.

Interesting. I Would think if there was some validation on those that wasn't right I would assume it would throw a code for them. so that's kind of interesting. Okay, so let's go back here.

and then let's look at this. um, the range switch in the internal mode switch I'm pushing on the brake I'm hitting the button. We still have a no start that's reverse and that's neutral which case the engine starts back in the park Again, no start. so let's see low high.

Yeah, it will not start and Park I'm going to start it in neutral, pull it back a little bit here and then we'll let it kind of clunk into park if you will. I just kind of wanted it to rock there I Want to see if that changes anything? It does because if I Let It Rock in the park, it definitely changes because it's in park right now and it's starting I put it in reverse going back in the park, shut it off and now it's starting. Let me um I'm gonna do some poking here and I'm gonna find hopefully find what we're looking for and you know, just see if we can get it to get it to act up. It's quite interesting.

I Would have thought we would have seen it right here, but let me do some poking around because I'm gonna have to look in some different modules and stuff. Um, and I think we'll find it so you folks stand by, just show you where I'm at while I'm poking around here. you know we can see like I say we're parked down there. we're parked there.

Push the button, you know, you know. Start Dash flickers I See this here. Uh section I have highlighted the power mode. It does show the crank requests going in, so just in case anybody was questioning that, that is there.

All right folks. let me show you where. Uh man. I Think we need to kind of keep it simple.

So Theory and operation here. Uh, you come down to the key start. So up above this it tells you the theory and operation on the cert stop system. We're not super interested in that.

Uh, come down here. So key and Start or the keyless start rather. uh. Ignition mode switch is place the crank position.

the signals uh supplied to the body module notifying the ignition is in the crank position. The BCM sends the serial data message to the under control module saying that the crank has been requested. The ECM verifies that the brake pedal is pushed, transmissions in park and neutral, or the clutch is depressed and that bada bing bada boom. It sends out a signal, turns on, relay, cranks the baby over.

Who remembers back when cars that said keys and no theft stuff. So that's pretty simple. Uh, what? I think is going on here because looking through data is of no use for us. But like I stated before we even got in here: I think these cars have certain elements of of redundancy if you will.

We looked in the data and we saw whatever we saw in there. We saw that there is a Uh I don't know what they called it. Was it A, a range switch or a mode switch? Uh, you know A B C P S You know all those internal switches We saw that. But what we're going to look at now is because I believe that the Park Neutral switch that we're looking for that I saw in that OEM diagram I Believe that it is simply a mechanical switch for Park in neutral and it is not displayed in data.

When we look at scan tool, it's not going to show us Parker neutral. It's not going to throw a fault if the ultimate redundancy would be if the two switches didn't match and then it would throw a code saying you know these two switches don't match or in plausible data received. That would be really great. but why rate that extra line of code when we don't have to? Not that I know anything about writing lines of code.

But here we go. There's six speed. ours is a 8l60. There we go.

Eight speed. We want to find this internal range switch that's a drive mode selector switch instrument Cluster, Transmission Manual Hall Here we go. So here down here, look right here. Transmission Internal Mode Switch I think this is the A B C D P S switch and all that stuff.

and then if I remember correctly on the OEM diagram this white with gray at Pin 35 Okay let's um let's do this. Let's come down here. We're coming Now we're gonna find here we go. Pin 35 I believe was the output and then this was low reference.

So beyond our mode switches down here, we have this switch right here. and let's follow those wires wherever they may go. Let's reset the diagram here. they're still going.

Where'd you go little fella? Okay, here they are. There's where they end up: Internal Mode Switch slow reference black with gray this is at the edge or that's at the training module and then Park neutral signal and that is at the ECM Gosh dang it not real good here without a mouse. Okay, so so that's it. So basically long story short, as they say down state this white with gray comes from the transmission internal mode switch.

the IMs for Parker neutral only I Believe it is strictly mechanical. this sends a ground signal to the PCM When it's in Parker neutral and it's not receiving that switched input in park, we can prove it. We can find the wire at Pin 16 connector X1 we can stab into that baby and I bet you dollars to Donuts that we will not have a ground signal there. So let me find the connector, find the easiest place to get into it and at that point we'll probably send them back to the dealer because this it has to be part of the valve body or something I would assume and the Dealer's misdiagnosis of it needs a battery.

At least now the customer can go and say Here's what's wrong with my truck. Can you guys please fix it? Um, that's what I assume so maybe they won't. Maybe they'll still want to put a battery in it I Don't know, but that's my hypothesis as far as what's wrong is the internal mode switch. The IMs is missing its ground signal so let's get after it.

Just recap here: Brief rundown underneath the vehicle I Have back probed into this wire right here. So this is the wire, the associate internal mode switch. It's grounded on this end through a low reference from the TCM So when this thing is in park or in neutral, this wire should be pulled the ground. This is the wire that goes to the engine control is the one that we can't see so to speak in data in the data list.

So I've gone underneath there and I took a wire back probe and I back probed into my glass line I think it's pin 35 and it was a white with gray trace and then I ran us a jump wire here on the outside of the car. Then I took a very low current test light, hooked it to battery positive and probed into that wire that underneath. Currently the vehicle is in neutral so that wire should be grounded. This is only a 75 milliamp test light so we're not going to smoke anything but the wire goes down and around and run through there.

So when we hop up in here, when we put this thing in park, that light should also be lit. This is providing that this ding dong probe the right wire. so let's see and it's oh onion hits. you can see that we're in neutral.

I guess First and foremost, we put it in drive like goes out. oops that's neutral and that is Park and see how it's not lit. Oops. Hopefully you guys can see that.

so we're in park and it's not lit. Okay I'm Gonna Go reverse neutral and then slip back up Drive Slam it apart. nothing I've got it on the lift. so I can't rock and roll it in the park.

but uh, that's proof. That's everything we need to know. Nothing that we don't There's the switch. it lights up in neutral, does not light up and park.

therefore it will not start. Whoa. You're too enhanced. so that's why it doesn't start.

But as soon as we. Light It Up Shut it off and that's it. So easy fix. Well, easy diagnosis.

I Don't know who's gonna fix it. Um, easy diagnosis. It needs a new transmission range sensor in a mode switch or whatever you want to call it. So that's it folks.

2019. underneath and show you where this is in case you're trying to diagnose your own. I guess I think it's been underneath? You guys always think I'm talking crap about Chevys because they rot away so fast. Let's have a little game around folks.

I Don't make this crap up. so she was back throwed into that connector up there. didn't Pierce any wires down here. It was pretty bad environment so we back probe there with our extra long test lead set 15 feet.

Let's see here it says that's what they tell me. So yeah I guess this is probably oh I've never had one of these eight speed tour apart. Not a big transmission guy. Um so I don't know if it's all part of the valve body or if the switch is separate.

but like I say it's got to be under warranty. but I think the Chevy dealer just needed to know that it's not just the battery, then it's actually a real real problem. So I feel the customer wants to do but imagine we'll get it fixed for free. So that's it folks.

now. a super complicated uh diagnosis on this one. Even though it's a semi-complex system with a start stop and all the computers and and all that stuff, you need to kind of keep it simple at some point. Uh, and then just realize that these manufacturers do have switches and I don't I don't know a better term but like some redundancy actually built into it.

It's kind of a shame though that they really honestly didn't write an extra line of code being that the ECM can see that switch and give it somewheres at least in the data. Reason for start inhibit. You know something like that To say the reason a starter is inhibited is because it's not in park or uh, you know Park neutral switches. You know, invalid data, You know.

So something along those lines to say hey, look, uh, truck's not moving Everybody says it's in park except this one switch. You know they do that with pressure switches. You know, like if you're Barrow and your map sensor and your boost sensor if they all aren't within, you know, a pound of each other. bang, you know we're going to be throwing codes for stuff like that same thing with you know, cool if engine oil and ambient air temp and coolant temp.

You know if it's at an eight hour cold soaking. All of a sudden one of them's like up here in outer space they'll usually throw codes against against that because there's always this little checks and balance but must be not on this. So no big surprise. and uh.

one thing I will have a big surprise about is if I don't see your comment in that comment section Questions: Comments: find us on the entity Facebook You guys know where we're at. Just remember viewers, if I can do it, you can do it. Thanks for watching.