O2 Sensor-No Activity Case Study: '04 Mitsubishi -Part2

[@dil6969]

This is one of your best video series. You guys went down the list, meticulously checking off all the variables, from the sensors to their circuits, eventually leading you to explaining the nonsense happening on B1S1 data stream. Safe to say, you both make a killer team.

[@wyattoneable]

I watched the entire video and can't pretend I understand the whole process but I can't wait for part 3, this will be interesting. Thanks for the good camera angles and great explanations.

[@richardreynolds8619]

If I remember my training at the Toyota factory the broom ground you are referring to is an electronic ground. It only switch when certain conditions are met such as a close loop. That is why the O2 sensors only start to work in close loop.

[@philliptipton9371]

Ok, try this for thought. Your V meter is a difference meter measuring the delta from positive to negative. The difference between the positive O2 V and the Negative 12v battery will be -10 to - 11 or 12v depending on alternator output. Yes?

[@johnmorgan1677]

Aah a temporary permanent fix. Got to love it. Nice diagnose, really loved watching it. So you really fixed it by using your own mantra, Lives and Grounds. The simple things.

[@mawolff23]

For someone with over 4K subs, it is impressive how many comments you respond to. I appreciate it very much, but even if you don't respond I just appreciate the work you put into your videos.

[@Eastahtata]

I think it would be more accurate to draw the break in the ground on the splice side of the chassis ground. The way Ivan drew it would represent a break in the sensing circuit for the O2, and in that case providing ground would be meaningless. I hope that makes sense. Just so people can follow along easier haha.

[@stevehunter3700]

Very true

[@ThePapa41]

Great Job of discovery to both of you, all the right steps, and NO guesswork!!! Louis

[@chuckreed2677]

If I followed correctly your problem is floating ground inputs to the box, not the box itself. I have 40 yrs. experience as an electronics tech for the military and what you call a rake ground was called a chassis ground as opposed to what you call a christmas tree ground we called DC return, or battery return in this case. I suspect that the grounds you are missing come from the chassis but the battery ground must have a good connection to the chassis at some point. Anyway at this point I'm guessing there is a bad connection at chassis somewhere. When you have strange voltages, suspect a floating condition, usually a bad ground. When taking voltage readings remember that the meter shows the difference between to points. So if your negative lead is on +10 volts and your positive lead is on +5 volts the meter will read -5 volts. Read both points back to ground on the battery to see what is going on. Thanks for making these videos, I always learn something when I watch. Going to watch episode three now.

[@bross956]

HaHa, my wife just asked me what could be SO important on Utube to DVR the Super Bowl. Baby, batman and robin just rolled out part 2... Great video guys...

[@PineHollowAutoDiagnostics]

+bross956 Wow man that's pretty awesome! I'm not really into football but just watched the superbowl...hats off to Manning and his team!

[@zoidberg444]

I didn't see that one coming. Its never the computer...
These rocket surgery collaborations between you and Eric are always fucking epic dude. My skill levels in electrical diagnostics have really improved watching you and Erics stuff. Plus its all fascinating.

[@PineHollowAutoDiagnostics]

+zoidberg444 Let's just say Part 3 is going to blow your mind then lol

[@baxrok2.]

Holy hell guys, this is fascinating! You two are killin' it with the virtual live analysis and fix. I REALLY appreciate the fact that you took time to include your use of the wiring diagrams and having us follow along, that helps so much. I agree, the Mitchel diagrams are almost impossible to follow especially for a DIY'er.
I'm still confused by the fact that the PCM has allegedly already been replaced. Plus, the mysterious alternator replacement for an overcharging problem bothers me.
One small request, please please don't call it the "white board of knowledge" that term reminds me too much of another much less interesting channel! lol
Can't wait for part 3.

[@zacatecano1986]

Baxrok2 i hate schrodingers cat .🤗

[@clydehanamaikai1394]

You guys killed it. Watched the whole 2 videos & going to watch the 3rd one now. Unbelievable diagnosis. I thought as soon as the pcm was replaced that was it. Until you gave more insight on what it will do after the initial repair. Never crossed my mind. Thanks guys.

[@randygudeahn7304]

I had to make more popcorn. yet another awesome series.

[@garlinwillingham7011]

I really like what Ivan proposed about a "temp" fix and let the drive cycle monitors run. Gotta be careful with "temp" fixes cause they can come back to bite you though. You guys put a great video together and I like watching the interaction between you two.

[@hightttech]

It's still a "temp fix" as long as it remains on the calendar to get a permanent fix (perhaps several calenders 😆).

[@nickatdallas]

Wow what a show👍
You guys should get together more often

[@ahill007ny]

Excellent case study cant wait for part 3!!!! I can imagine the amount of codes that showed up when it ran the drive cycle.

[@haywardsautomotive6156]

Great diagnosis. Lack of computer grounds, internal computer grounds or or short to voltage makes an electrical circuit wig out. In the end you went to battery - with the meter lead and B1S1 grd read 12V which it should not have so when the computer fried it is possibly picking up the 12V from the 12V side of the 5V regulator (purely speculative) and at the same time lost the O2 sensor computer grounds internally. That also explains the -6 & -10VDC you were showing which was a short to voltage internal of the computer. I wish we could have computer internal circuitry and then wouldn't have to guess but I agree with all the sensors sharing a common internal ground. Awesome diagnosis & brainstorming the problem solving. Explaining to the customer the other possible associated problems with the catalytic converter and drive cycle issues will produce good customer relations. I enjoy watching your's, Eric's, & Paul's (Scanner Danner) channels especially when you get together b/c you are thorough and explain your theories and diagnosis process better than almost every channel out there. Thanks & keep them coming! I still would've disconnected the PCM and made sure the 12V went away form the sensor ground just to be sure it wasn't coming from somewhere else and taking out the PCM.

[@hawaiianf1504]

Luke - I felt a powerfully strong and yet great disturbance in the Force!
Ah Ha!! It's Ivan and Eric using their super powers to heal the sick. Great Video! Wishing part 3 was here already.

[@SouthMainAuto]

+Hawaiian F150 $50 in my paypal and I can tell ya the answer haha! No seriously....I wouldn't... well maybe I would

[@hawaiianf1504]

+South Main Auto Repair hahaha!!

[@PineHollowAutoDiagnostics]

+South Main Auto Repair Everyone loves these bizarre "see if you can guess the problem" vids...I'm looking forward to Part 3 myself!! :)

[@hawaiianf1504]

+motoYam82 - I second that!!

[@willemstreutgers1154]

As the neg.voltage on the "internalground"changed from -6 to -10 volts. I suspect some shortage in the PCM on the internaleground lines on the board, might be a loose part or debris moving around there.
A can hardly wait for part.3 This is a really good vid guys !

[@lornaz1975]

EXCELLENT!!!! Wonderful educational vid!! I know you are a busy man but we would love more long detailed well explained vids like this. Not that your shorter vids are bad they are excellent as well but this vid was so detailed and well explained. Move over Scanner Danner! Thank you!!

[@stuzman52]

Nice case study Ivan and Eric. Looking to see the final fix...

[@SouthMainAuto]

+stuzman52 Oh it is a good one Terry :)

[@stuzman52]

Thanks for commenting Eric and seeing what you guys came up with for the final fix.

[@Bereft777]

Ivan and Eric I just stumbled across this. Your O2 wizardry is outstanding. What a shame about that car...I wish i could get hands on the original PCM.

[@int53185]

Gotta watch those pesky PCMs. Had a '97 Bonneville that kept throwing an EGR code. Went the idot route and replaced the EGR valve. Low and behold all was well for a week and then viola' the code came back. Suspected the PCM. Opened up the case and found a small shard of aluminum that was grounding out the PCM and causing the code. Removed the shard and all was well.

[@PineHollowAutoDiagnostics]

+James Last Ha that's a beautiful fix!

[@547Rick]

WOW another trilogy! Can't wait for part three.
Nice work boys!!

[@gerardkavanagh144]

Well done guys; judging by the state of disrepair of the wiring from the first garage's efforts; I wouldn't be too surprised to find out that he had used a junkyard PCM replacement.

[@dcomputers]

most likely. because the a new pcm cost alot. using used parts can create other variables

[@HePBHuq]

Thank you for the detailed explanation! It really got me out of a situation with a vehicle which had the same symptoms and turned out to be the same fault for one of the two sensors. :)

[@DJ-tn7vj]

Fellas, this is one long diagnostic video but I watched every minute of it. Couldn't wait to find the fix.

[@CoolAirVw]

Nice diagnosis. Very logical and structured. thanks for sharing.

[@dannycole9401]

I love the information. You both make me diagnosis stuff more methodically

[@motorcyclesandridingfree2899]

I was going to yell at you for not checking computer grounds but the Eric stated you did as a lot of times computers have individual grounds for separate circuits especially foreign cars. Good work guys think you make a good team.

[@colinmoorelovethemusiclook6506]

Wow, what a rabbit hole, well done Thanks

[@mawolff23]

Thank you for being so quick with part 2. Great video, keep it up!

[@PineHollowAutoDiagnostics]

+WRX Mike haha didn't want you guys to wait too long! I'll let this simmer for a few days before releasing Part3 with the final fix....and it's NOT what we expected!!

[@mawolff23]

+motoYam82 ohhhhhhh now you have done it!!! I'll be looking for that video everyday now! Lol

[@mbtjr]

+motoYam82 A few days? You're killin' me. This is a cliffhanger

[@SouthMainAuto]

+motoYam82 Oh man your gonna make them wait it out!?

[@Bob33O]

+South Main Auto Repair Yea really!!!!

[@Discretesignals]

Eric was more excited than a sugared up 10 year old at a sleep over. : )

[@sandyande]

Brillant, better than breaking bad and homeland combined many thanks, sandy

[@mechanicmatt871]

You two work together really well. Great diagnosis there :-)

[@marcellusorlando3414]

I know it's kinda off topic but do anybody know a good website to stream newly released movies online ?

[@ariantoby7359]

@Marcellus Orlando i dunno I use Flixportal. just search on google for it :) -arian

[@marcellusorlando3414]

@Arian Toby thank you, I went there and it seems like a nice service :D I appreciate it !!

[@ariantoby7359]

@Marcellus Orlando Glad I could help :D

[@offtwoaces]

Great job of troubleshooting the problem. I would be tempted to open up the ECM and trace out the signal grounds to the O2 sensors. I'm wondering if the ECM was originally designed to handle both 3 wire and 4 wire O2 sensors with an optional ground connection/jumper inside of the ECM. When using 3 wire sensors, the ground would be removed. When using 4 wire sensors, the ground would be installed. Of course the two versions of the ECM would have different part numbers so that wouldn't explain how car ended up with the wrong ECM.

[@akdenyer]

Hi Eric,
What has happened here is the previous people were trying to see if the PCM was reading the sensor and connected 12V to the ground of the sensor. Not using a test light, this would fuse the negative track inside the PCM. The B1S1 ground circuit is used by other circuits as a ground and they are referenced to +12V this would rise the ground voltage to some voltage a lot higher like your 6,7 and 9V. The signal wire is pulled down via the potential divider. Hence your scope would see -6,7 or 10V. I was shouting at the screen, check the PCM ground. Eventually you did and found the fault.

[@rockynix7731]

This has been a very interesting video .. looks like Paul thought this young man right in diameter and trouble shooting ....

[@ponyhorse127]

Great video Ivan!!!....the real fact is that PCM is bad!!!...so it needs to be replaced!!! no matter if someone replaced earlier!!! About the grounds...let me tell you my humble opinion.....every car was designed to trip a given collection of codes!!!...the wiring and electronic circuitry must be designed to accomplish that goal... in modern cars every sensor has independent wires in order to be able to trip diferent fault codes from the given collection, that is why every sensor has its own wires and grounds!!! Internally the PCM is a very complex electronic circuitry and has conections to body ground, and individual ground stages. If you jump-wire the grounds it might lead to a non-capable trip code situation of a undetermined number of codes of the general code collection. It might work fine for sure (because you know really well how the car system works and you are very professional and skilled guys )!!! but the PCM could became unable to trip some codes because all the O2 sensor grounds have been connnected together!!! I dont know if I did explain myself!!!!...the idea of provide external ground conection to the sensor is a good fix for that given condition, but some codes would be unable to trip again, no matter if the sensors are good or bad....but anyway that PCM is bad (half toasted) right???.... thank you for sharing all this info guys!!!....Ill be waiting for the final video of this tricky case!!!! :) :) :) :)

[@PineHollowAutoDiagnostics]

+Fidel Robles Yes, every wire is there for a reason! Those electronics engineers are definitely sharp guys, but no one can predict every single possible fault scenario...that's why diagnostics is often so thrilling :)

[@marshalllarson8970]

I was a computer engineer from the 70s through the 90s and that "broom" symbol is used interchangeably wit the inverted tree one.

[@Shirkatron]

In circuit design for grounds… the broom symbol is chassis ground and the tree symbol is circuit ground to a common source [battery negative]

[@windward2818]

The HEGO signal output to the PCM should interface to a relatively high impedance input with a diagnostic technique to detect an open circuit in the harness, it should also detect and be protected against a short to vehicle power +12VDC, which would be the most common short to power. How and when the DTC is reported relative to a drive cycle and lighting the MIL is manufacturer specific, although they must include the diagnostic as per OBD-II. The PCM will have a smart low-side driver circuit for the heater control.
Usually, the heater OBD-II monitor is a two trip (qualifying drive cycle) DTC. I should add that even though I use the term drive cycle, what I really mean is, the required sequence of events (sequence of vehicle operation) that constitutes a drive cycle. It is possible that the qualifying events are related to things like: Key-On Engine-Off with a pause before starting (like five seconds), Key-On Engine-On and at operating temperature, and other qualifiers that may not require the vehicle to attain a minimum speed, so in this case, the drive cycle, actually does not require you to drive the vehicle.
You can also run into the case that the vehicle is operating normally but you still cannot qualify a monitor. A good example is the EVAP monitor, which in my experience will not qualify unless the tank is between 1/4 and 3/4 full, and is a two trip monitor. So, conceivably you could have just serviced the vehicle, which required a battery disconnect, with a full tank of gas, and you can get all the monitors to pass except EVAP, due to the tank level not within range.
Another major challenge is the OBD-II CAT Monitor which has slight nuances between different OEMs. It is a two trip monitor, but the qualifying conditions as related to vehicle speed when up to temp can be very challenging to meet in every day driving depending on your circumstances. Older cars 1997 and to about 2006 may have a three tier set speed timer, which has to be satisfied on two different trips.

[@sombody6507]

I think the signal wire is shorted to the heater wire, the live data will
only show 5V because it is a low voltage circuit (computer doesn't expect higher
voltage). You can jump the signal wire of one of the other known good sensors to
battery voltage (using your test light of course) and see the O2 data PID, it will not
be 12V but 5V (on the manufacturer specific) or 1.275V (on the global OBD-II).
Nice case study by the way.

[@squareyes1981]

Nice case study. Thanks for shooting and sharing it.

[@hauntedro]

Can't wait for part 3 guys!

[@jeffb6605]

This is a serious Bromance

[@richardjones3112]

Absolutely fascinating.

[@raymondjones7489]

If I keep doing this I won't have go back to school to get refreshed!!😁😁👍😎

[@190055joe]

As a tech myself Im always careful when back probing for a GRD or VE+ back into a PCM or any processor because if the current is to high you will burn tracks on the PCB .

[@puffstuffu2]

I forgot to say outstanding effort on this case study ivan and eric. looking forward to part 3

[@bigmac965]

Ivan: "This car is just kicking our a**, man!" Bwahahahahahaha... Man, if anything needs double-teaming, it might be this Mitsubishi! It may be haunted!

[@Jon.Rushing]

Ivan, I saw on another comment that you are going to make us wait that is so evil to lead us on like that :) Great relic you dug up in the archives. I did suspect the computer in the first part but as Matt says you need evidence. I have had great luck with BBB industries' wire diagrams; every one I used was correct for my 98 S10 but that is probably because my S10 is turning 18 years old in May so there was no rewriting of the factory stuff. That's a tough one to explain to the customer that if you put a new $300+ computer in it that won't 100% fix the money light and the money light will come on sooner rather than later and then they would need to drop $1000+ on a new cat. If it was mine (which I would never buy a Mitsubishi and wouldn't drive one if you gave it to me) I would send it off to be turned into tuna cans! I am looking forward to part 3 "the real fix". You need to crank out 1+ hour long videos everyday and so does Eric O. :)

[@PineHollowAutoDiagnostics]

+Jon Rushing No worries Jon, there's always more long uncut footage in the archives waiting to be released :) Just need to find some time to sift through it all!

[@MrKingdavis13]

I am watching this video 3 years after the fact but I bet there is actually nothing wrong with that computer, it was just replaced with the wrong certification and doesn't have the wiring for the additional 02 sensors. I hope that the customer doesn't go back to that garage that they took it to before in the future and that part 3 fills us in on that aspect.

[@glenharper3136]

You 2 make a Great team!

[@mawolff23]

OMG a Trilogy!!! Love it

[@bobvincent5921]

Thanks. A wild guess, the heater is leaking to the OX sensor.

[@williamhanna5224]

Awesome video Great work Guys !!!

[@turtlezed]

sometimes brainstorming like this has 1 participant lagging slightly while mulling over the info in their brain all the while the other ones talking and hes trying to process that as well. you have different styles but you both got to the same place. Having access to quality wiring diagrams is an absolute necessity or otherwise you may have arrived at a pcm replacement without ever going past that point and digging any deeper. Great depth of knowledge fellas and enjoyable to follow. if you'd decided to jump those grounds as a cheap fix, it would be interesting to see whats going on in the pcm to see if water ingress had rusted out the ground common terminal, if you were changing it that is.....maybe i need to watch 3rd installment?

[@chungaleta1234]

I'd join those four sensor grounds to an external ground spot and drive it for some cycles to see if the cat is toasted, I'd also inspect the 4 ground pins at the internal side of the connector for a bad solder point at the board. I would,, I would, but since it is neither my car nor my channel,,,, I'll grab the popcorn and wait for part 3. LOL

[@ianlevine273]

Great case study. Thank you.

[@samrugtiv5563]

I was right ,you guys are the best I have seen on the east side,now tell Ivan to make a big pot of soup .ps dam good job sam

[@WCSPete1]

Truly brilliant.

[@TexasEngineer]

Always check your powers and grounds first, could have saved a lot of time. Floating negative voltage because of loss of ground. Replace PCM with remanufatured one with warrenty. Strange, replacment PCM had same issues as first one.

[@benfreeman9717]

This is great material guys, keep it up!

[@rosscampbell6644]

awsome so my 74 j 45 is known good 1carb and points still runnin my brakeleen safe in ma cupboard 80 camaro 94 silverado still run.. u.. guys are best on youtube

[@PineHollowAutoDiagnostics]

+Ross Campbell Keep on rockin' dude! Carbs and points all the way!

[@nandor690]

Awesome video. I was thinking for sure all the grounds are connected internal to bat ground cause when you were back probed and showing -10v then started the car the voltage on the ground changed with bat voltage. Meaning you have a complete brake in the ground internal which is way you were seeing battery voltage on the ground.
I think I'm right. Iv been learning with scannerdanner and now you guys so correct me if I'm wrong please.
I like the videos with both of you guys.

[@rsanchez5676]

@Scope on a rope” freakin hilarious!!!

[@gulliver3644]

Did y’all check or replace the gas cap? Goodness! Making it rocket science aren’t you guys? That usually fixes 90% of check engine lights.

[@TheChristopher1972]

Check the ground sensor wire at the pcm to see if there is a common ground for all the O2 sensors

[@roadkill5333]

Ok, so I have a question. Or a few questions, as the case may be. But don't intend to cause any problem. When you back probe the ground sources, at the PCM plug, is it possible that the ground sources were good, but not going thru the plug, into the PCM correctly? Like, if there were corrosion, or a bad pin connection, or even some spread pins, from the last guy to work on it? You showed that the multiple ground source wires were solid connections to ground, but not that the PCM plug was solidly connected to those grounds in the PCM connector. Also, could there also be maybe some broken solder joints at the plug, causing no ground on A SOURCE GROUND to the O2 circuit. I assume that you consider any circuit fault inside the PCM, to be a reason to replace the PCM, but it could be possible to attempt a repair, before spending money on a new one. And didn't you say that the first guy already replaced the PCM? Or was it that he tried a different one, with no results, and put the original back in? Thanks for the very interesting case study!! You guys sure did put in a lot of effort on this!

[@EKHondaMotive]

Gentlemen, great collabo!
Just a word on the direction the diagnosis took...
Are not PIDs that describe voltage as "high" indicative of a lost ground?
I would think that had that PID's DTC been investigated first, the video wouldn't have been as interesting!
Cheers! -100

[@theoldwizard998]

I have to make a third batch of popcorn now !

[@garysmith9772]

Hook-up your scope set to a/c at the battery and see if your getting any a/c signal with the engine running.

[@ForTheManDIY]

I suspect that someone before you shorted the ground to 12V, possibly while fiddling with the heater issue. Another remote possibility has to do with microcontroller pin definitions. It is remotely possible that a glitch in the PCM PROM software has left the ground pins for the O2 sensors as inputs vs output pins. Or the analog chip feeding the PCM has lost it's ground due to the 12V short described above. The most likely scenario is the short to 12V as I previously mentioned. As for the max indication, computer registers usually set the most significant bit (MSB) to one for a negative number. The PCM is not looking for a negative number so that MSB tells the PCM that the number is very large positive and assumes . This is my answer without seeing part-3. So now, where is the negative voltage coming from?

[@mikem1014]

i would ohm the 4 oxygen sensor grounds at ecm to see what if any are tied together

[@jamesfenton7338]

It's a "Chassis Ground Sign", apparently the pcm is not grounded externally.

[@johnchristopherson2718]

So is the magic environmental air sensor next to the headlamp fluid indicator module? :)

[@naushadali95]

Great diagnosis.

[@brucebratschi4300]

Very interesting stuff. Throw a couple used converters on it? No warranty? Lol

[@albutterfield5965]

Mr. Mellow and Mr. Hyper. Trouble shooting can sometimes be a slow and boring process jumping around and tweaking stuff does not help.

[@ericcorse]

Good video guys this took a thinking cap.

[@wysetech2000]

Well...that was great detective work by both of you. Eric, didn't you say that another PCM was tried already? I haven't worked on one of those turds in a long time but I do know that some manufactures do weird things that make no sense at all. You said that the PCM had a plastic case but it appears like there are metal straps on it. Hard to tell from the video. I just wonder if the O2 grounds are connected to the case somehow. I'm probably out to lunch but a quick ground wire on the computer metal parts would prove that out. Maybe too much popcorn and rye whiskey has effected my brain....Ha.

[@PineHollowAutoDiagnostics]

+wysetech2000 Popcorn and rye whiskey...that would have been a great conclusion to this one lol

[@IamReadyToRock]

increíble. From Peru, thnks

[@mtoddvan]

Lol ok, the controller module is grounded to chase/ battery negative ground but internal it creates an independent isolated ground to reduce noise & rf interference, it also creates an independent isolated positive supply for the same reasons, usually this is accomplished by one microprocessor that supplies different voltages for the signal data usually 2 to 5 volts positive & negative this allows for isolation to keep from overvoltage to low voltage circuit (signal. etc..) . Now let's look at the -9 volts you where seeing on B1S1 when you connected the wiring harness back into the module. O² sensor +2 Battery voltage -11 negative , so 2-11= -9. What you're seeing happen is a internal short in the isolated circuit inside the controller probably diode blown on the negative isolated side yet the positive side is still working isolated on the signal wire hence giving you the negative reading before you grounded the circuit straight to battery. I'm not familiar with all the internal layout of this particular controller, but it's a standard process for control circuits. Obviously you are knowledgeable enough to use caution in testing these circuits without a load as you demonstrated here & in other videos you've uploaded. Probably more than likely the last shop wasn't & hence damaged the controller unintentionally, but that's only a possibility not an accusation. Hopefully you'll find my comment interesting & look forward to anyone that has a comment. Oh final note if anyone is having trouble understanding the math above think of 2 separate batteries one that's +2 volts (O² sensor) & one that's -11 (isolated controller circuit)

[@int53185]

The way this thing is buthchered, hardwiring the grounds wouldn't be a bad fix.

[@SouthMainAuto]

+James Last Oh my gosh butchered... this thing was a virgin compared to the Jeep vid Ivan did... now that thing was "special" haha

[@Banshee365]

+South Main Auto Repair "Custom"

[@juergenscholl2843]

Still with the question where the voltage potential on this B1S1 ground wire comes from ...
If the 4 O2 sensors really share internally the ground connection wouldn't you see this " bias " voltage on all 4 of them while th O2s are unplugged from the harness?

[@PineHollowAutoDiagnostics]

+juergen scholl Great point! This was a real mystery. And it wasn't a hard "short to voltage" either...wasn't enough to light the test light. I would think a "ground is a ground" and they should all be tied together! Apparently not on this model lol

[@philliptipton9371]

I'm thinking of a bank one system ground which has high resistance progressing towards and open circuit as current flow heats it's poor contact.

[@sv_endless6340]

I am watching this and comment as you go, did you check the B1S1 unplugged and probed the plug coming from the black box, checking the harness signal then from the box, and then checking the box probe the wire.

[@alejandrob10]

So it's ok to hook up your test light to battery positive and test grounds at the ecm or hook up your test light to battery negative and check voltage at the ecm? You won't fry anything in the end?

[@PineHollowAutoDiagnostics]

+alejandrob10 Absolutely. It's really quite difficult to fry anything with a test light :)

[@corkforbrains]

Hey guys.. I'm the LAST one you should be listening to here about this, but I spent 20 years in communications and I wanna toss something out there.. There ARE electronics that have in essence 2 grounds.. One is a case ground and it's common to the battery ground. It's principal purpose is to bleed off stray electrical current. There is ALSO a "ground" that serves as the negative side of the electronics internal to the device. It ORIGINATES and TERMINATES on the circuit board inside your component and often has NO connection to the battery ground. It serves as the negative side of any circuitry on this circuit board and terminates on a BUSS ( a common point of connection on the circuit board, often isolated from chassis ground). It is called "common" at times to make a distinction between the two electrical components ( although one of them is actually an ELECTRONIC "ground".) Just tossin out straws here.. I know that you gotta be real careful trying to measure things on an electronic circuit board or you can blow stuff up real easy. Once again, bear in mind I'm not any sort of electronics wizard.. just a guy tryin to help.. Excellent Video!!

[@RipCityBassWorks]

A P0420 on 4/20 is pretty fitting.

[@PaulCTownsend]

GOOD JOB YOU GUYS.

[@catfishsnagger3284]

What is the link to the BBB website for the wiring diagrams?

[@johnf3278]

Wondering....if it's not grounding internal you ground it external how did it get the signal like your volt meter no ground from inside out how can get from outside in????

[@j.t.johnston3048]

I'm only part way through part 2, but I'm guessing a broken ground between the B1S1 o2 sensor and the ECM. Will watch through all the remaining parts and see what you guys figured out.

[@j.t.johnston3048]

Another possibility would be a broken ground trace inside the PCM. Just speculation at this point.

[@chiefeaglebear2320]

i was thinking those grounds on pcm should be checked back when tracing signals and grounds on sensor im glad my direction is getting better i was wondering are those good grounds if not that sure would make the signals wonky !

[@psdaengr911]

Whatever happened to "power and grounds"? Could have checked that before suspecting O2 sensors.

[@richardreynolds8619]

Could the heaters be shorted to ground?

[@randy1ization]

did u leave a link to the free wiring diagrams?? is it BBB?

[@macorazonpartosa2886]

I think the oxygen sensor ground is not grounded to the sensor housing