So at about 20 mins, you actually said it.. The PCM has the ability to put out voltage, but no amps. And this is the biggest problem with Chrysler computers that have power switched accessories. ( not sure if this is true about those that use TIPM) If the original o2 heater power circuit shorted, the computer driver gets smoked. Chrysler does not protect its power switched outputs via fuses in almost all cases, and if they do, it's usually over fused ( the fuse is too big). They haven't done so since the SBEC/SMEC days! ( in those days, shorted injector, shorted ASD relay etc, bye bye PCM) You nailed it. Sometimes it's a hard pill to swallow, so we keep trying to prove what we already know...
At Ivan, you're probably too young to have ever worked on 1, but the old Chrysler M body cars with the ESC computers were notorious for blowing computers due to shorted solenoids like EGR and purge. They would get full of condensation and short. The computer would go into a limp in fixed fuel and ign timing strategy , so the car would run, but have low power and really bad mileage. Techs would replace the ESC and it would work for about a day, then same scenario. Because these cars (81-89) never had a check engine light, techs that didn't have the plug in Chrysler scan tool, which connected at the ESC, could never check why the ESC failed much less read codes. They were a nightmare in the independent garage field. Unless a tech started poking around at various sensors and actuators, he'd never find what killed the ESC. The ESC was not protected at all except for main power inputs via fuse links. Back in the mid 90s, people would bring their cars to me and I got dubbed 'Mr. Chrysler'. Top things that killed the computers were shorted 02 sensors, EGR sols, purge sols, and carb throttle stop switches, all controlled by the ESC, none protected by a fuse. A little retro for ya!
I think I know the secret. You must become sleep deprived to understand the inner workings of the computer-controlled motor vehicle. I mean how else can Keith get through 20-30 vehicles a day. Good diagnosis Ivan. Without knowing the theory of operation you worked it out to be able to call a bad driver in the PCM. Thumbs up man
Experience does that. Try explaining to an end customer they are paying for your experience not time though and watch their head explode when you diagnose it in 10 minutes and still expect the full invoice amount. I don't know, but I think Keith solely works for other shops when they get stuck on something rather than having to deal with the irrationality of general public customers. Wise man. That's not a sleight on the customers BTW, we're all irrational idiot customers when we get outside our sphere of knowledge and it all becomes mumbo jumbo and unicorn farts as someone tries to bill a gadzillion bucks for apparently just standing and thinking for a while :D
You answer your own question. Then question your own answer. That's why Keith can go through so many diags. You are great at what you do brother. Be more decisive. Trust yourself. We are reverse engineers. Clearly the original engineers didn't get it all right. So we aren't either.
Lovely place to locate the PCM. Keeps it cool I guess... water cooled! Nothing new though. Used to own a Mk3 VW Golf or Rabbit as you may know it (1996 era). The ECM for that was located in the gutter at the bottom of the windscreen. When you read "access the ECM by removing front wipers and plastic rain gutter trim" you have to double check it's not 1st April. That said. Never had any issues with it to be fair.
I think I do 20-30 vehicles too ... per YEAR!! 🤣 This is one of those cars that would've had my blood boiling. Guaranteed it would've taken me 12 hours to be absolutely certain the PCM was at fault. My main problem is I get so frustrated, the last thing I want to do is experiment on good circuits. The only cure for that in my case is to troubleshoot American cars built before 1981. 😁 I hear you on the engineering! Both my '86 Grand Marquis AND my '93 Volvo 940 have the ECU in the right side passenger footwell. Only seems logical to keep a COMPUTER out of the weather and road salt! Every year these vehicles amaze me. I don't know how anyone in auto manufacturing can sleep at night. It's all about $$$$ today ... Nice job being patient with this one! 👍
Just for the fun of it, I would have applied 12 to the upstream heater and checked if car went into closed loop. And O2 performance normal. Great analysis. Fun.
As soon as you were able to instantly pull down the upstream heater output with the testlight it was clear the output on the ECM was pooched, regardless of the O2 sensor heater being open circuit/connected or not. Otherwise it would take an appreciable/measurable length of time for the ECM to stop trying. That's just the way input/output stuff is programmed. Outside of racing I'm sure the delay for determining an input to be valid is about 0.3s, a blink of an eye for us humans, but an eternity for digital logic. Connecting the test light just immediately influenced the output, hence the output was pooched.
thank you Ivan for sharing , I have not got into those too deep, how ever I remember a 04 pt cruiser that went to the shop with up stream and down stream o2 heather codes , both new sensor , it was not my vehicle it was working other technician ,I told him to use ntk per Scanner Danner video on this case study, this tech told me 02 sensor is 02 does not matter he did his test and conclude to replace both 02 sensor with different brand but still not ntk, guess what both codes returned, they told the customer is computer so in about 4 month it comeback for emission test, they gave me that to me , for diag I recommended with out doing any test at this time ntk both 02 sensor , the service writer told me those sensor are new and I said I can diagnosis computer issues after I get oem sensor only. and attempt to run monitors I installed the 2 sensor and clear the codes , by the way it had transmission codes before the first time they installed different brand 02 and now , I clear codes run all monitors next day in the morning all run no codes present on any computer , next oil change in about 3 month I check for monitors and codes and was clean. at this time I played with some scope test, I realized on the ground side for the o2 sensor they send 2.5 v they call it floating ground , yellow lead on signal wire. if you connect your scope and connect black lead ground on battery it swing from 2.5 to 3.5 volts, now connect the ground to sensor ground and it swing from 0 to 1v as normal o2 , any way that is how far I get , reality is those NG Chrysler computer like ntk only probably the sensor has some compensating for floating ground or who knows . the previous set of o2 sensor were denso and second set were bosh. it pass smog now , I get weird diag sme times with people force to do keep the vehicle on the road to registrar , smog license bring me more fun diag. thanks once again
great video bonus .... quick tip tuesday on friday a piece of heat shrink on about 90% of the test light metal tip will keep down on arcing to ground no welding allowed while testing lol
no problem ivan , hope that helps someone else out there as well ... you did give me a great webpage to get wiring diagrams from ( bbbind.com ) so just throwing one back your way
Great video Ivan, I was wondering , the Heater Duty cycle is controlled indirectly by the Engine temperature. You didn't mention about a possible ECT failure, but I guess if there was an ECT failure , the code would have popped up and also the rear O2 would have had problems with the heater circuit. Thanks again.
if I was in doubt, I'd repeat the same test on a working O2 sensor/bank. also a simple resistance test of the heater itself, compare with other bank or see if you can find known value for it. other than most being 5 to 10 ohms :)
Not that it matters (because this is still internal to the PCM) but the wave form you are showing at 23:41 is a classic "current limit/fold back" wave. It seems like the current limiting circuit is actually "blocking" the signal from the CPU. This make sense, because the data say the software has it turned on 100%.
yeah looks very much like driver issue . Testing the next era of motor cars will be fun with more computer strategy, bias voltages, dual side controls and so forth :-S This one potentially easy with basic test procedures, never easy calling pcm though unless real clear cut evidence . Got to love under hood pcm locations and this front wheel well takes the biscuit lol, the must want early failures and bigger expense in light front end collisions . Can't see how Keith can do over 20 cars in a day, if give each car 30 minutes plus mobile commute time you hitting close to 12hrs . I don't do more than 12 cars and that from a shop which far less downtime over mobile, sure some things take 5 minutes but most are 30 minutes to a good hour .
The voltage without amps on upstream O2 might have been the voltage driving the power transistor / mosfet, leaking to the output. If there is no voltage or the transistor / mosfet has failed and does not turn on, you might see just the driver stage signal, which can put out only a few milliamps, enough to turn on the driver transistor / mosfet. Any load will pull it down. Same thing when the power transistors fail in audio amplifier, you might hear a very low volume sound, it is the driver stage.
Just to avoid confusion in the analogy in audio whet we call the output stage is what the pcm calls the driver stage. We could have easily gone for the same terminology but NOOOOO! 😂
What if you shirted the downstream o2 heater control to upstream and cut the upstream orgianl control wire to resistor to ground(make it belive all is ok), would it have then working o2 on upstream too? ...Or would it have bean too much for the downstream driver to handel?
What are you seeing Ivan on your Scope is the MCU signal to the MOSFETs Gate, this is a typical sign of a Transistor failure, being unable to carry load though its electro-Chemical bridge is just like having a weak/shorted electro-mechanical relay unable to latch
When you showed the test light killing the drive i wondered if the manufacturer was using a heater with a higher resistance, just to be a pain in the arse!!. (Special part). The downstream one seemed ok with a test light, but the plug is different, perhaps trying to stop you swapping sensors maybe. I'm sure you found out the truth, so don't forget to leave us on a cliff hanger Ha ha :-D
Still makes me question powers and grounds on the PCM if it was unable to light the test light. Like Ivan said, you'd think that the upstream and down would be on the same connector and pwr/gnd but maybe not. I'd hate to throw a PCM at it and still have the issue.
seems having the test light on the sensor wires is more or less shorting it, making the ECM think it's shorted or stuck O2 and seems to be turning the heater off,. would have been nice to see the light each time it started, to see if it powered it on or not when it briefly claimed 100%. thinking it was lighting and going off before you got out to see it, if I'm inside a vehicle, I put the test lights up on the windshield so there's no missing it. been burnt too many times that way :)
damnit, posted too soon in the video again :))) still wondering if it sense no or shorted O2 and doesn't try to turn on the heater.. nothing surprises me with crapslers.
Love Bonus footage.....Kieth must be getting rich, sometimes people get lucky and hit on the trade they were meant for, and totally fly past anyone else in that field, and yes get rich. Or at least afford a swimming pool.
@NewLevelAuto is this true? Can this cause the heater circuit driver on the computer to go bad? "If this all looks good, we will need to see if the ASD control circuit has voltage on it with the key off. When there is a voltage on this circuit, it will damage the PCMs heater monitoring resistor in the PCM. We will need to check the brown/gray wire at the asd relay for voltage with the key off and if there is voltage with the key off it will damage the PCM."
Up Date on my Tacoma problem....I Fixed it, in the end it was the Dist, apparently the Signal Generator was starting to go bad and was not sending a signal to the ECU that the plug had been fired, so the ECU would cut fuel and spark and a split sec later it would send signal again, so I was getting a bumping feeling going down the road. But Hey I fixed something The Toyota Master Techs, could not find, only took me a month :) New OEM Dist from Toyota was 550.00 Ouch. But the little Tacoma with 257,000 miles is humming down the road again. Yea
I saw them on EBAY for anywhere from 99 to 250, but I could not trust them. This took me to the very end of my troubleshooting ability, But I learned a whole lot about my Toyota, and in troubleshooting in general. In the end I learned you have to understand how all these electrical parts work together, because if you dont, you end up chasing your tail. It was not a easy problem to find. But because of the Videos you and Eric have posted through the years, I knew I could figure it out. Dont get upset, get educated .
This kind of head scratching drama makes a simpleton like me want to just own and ride a bicycle. Cheaper on insurance too. Maybe on to something since I am retired.
Both my '86 Grand Marquis & '93 Volvo 940 are pretty hands off as far as repairs go. Neither one gives me any grief, unlike my '07 Silverado - always something new with that one. Been driving around MA with a "R" on the windshield, since the stupid monitors haven't run in 2 years! Who knows why ... and I don't have the patience to find out! As long as it starts and runs when I need to tow something, I'm good. :)
Hey guy; Tom here, A voice from a while ago. I have been out of commission for a bit and am back on the 1999 Dodge Durango no buss. The code that shows up when I hooked up the new scanner is P 1687. I'm still worried that it might be a wire issue. I have been trying to test wires for shorts and am overwhelmed. Any direction you could send my way?
No one can deny that you're persistent. P.S. What are you doing posting videos at 5:55 a.m. ? When do you (and Eric O. at South Main Auto) finally go to sleep?
I've got you all beat in the SLEEP category - 10 hours last night, and I could've went a couple more if I didn't have so much to do today. 😁 I'm the polar opposite.
I'm going through a very similar issue can anybody please help me? Have a 2005 pacifica 3.5L same location of computer on this video so same vehicle basically. Code is p0131 heater circuit low voltage, o2 sensor is a brand new denso and code still pops up. Just replaced the ecm through ebay with vin programmed and I still get this code. Please help I heard something about the fuse box being an issue or something. I get good ground at my 02 connector but no 12v. Thanks.
HAHAHA! I noticed that too - they didn't even cut the zip ties they threw up there! Someone wasn't getting paid enough to deal with all that. 😁 My attitude would probably be the same after spending 20 SECONDS in that traffic down there ... 🤣
I had a similar situation on my dodge that ended up being pin fitment of the PCM connectors. There are no test points on the PCM board to tell how well the signal is getting onto and off of the board (so the factory basically considers the PCM and its wiring harness to be ONE part [which is a PITA to change]) so I'd really caution anyone working on a modern Mopar to do the drag test with a appropriately sized pin (probably .055" on these) on the connectors
I'd have been cranky early in and shorted the heater wire to ground too see if the ECM said "shorted to ground/low" or nothing. as it should detect when key is flipped on and not try to power on "hard/full" anymore. then again I hate the garbage in vehicles and still prefer smoke clouds to find the issue :)))
I'm not sure it would have thinking/guessing in terms of the ecm internals, then again I could be off target on it's design and it may still sense it proper, so if you get one you're sure is bad again, try shorting it to ground! for me/us/the world :) it would have been great if they had the original O2's for you to test and look for physical damage, like did it have an intermittent short to ground and the ecm slowly cooked, in theory it should detect that and set code, but we all know how codes "always set and are right" HAH!!! it would be neat if someone could tear into bad ecm with same issue, but I suppose it's near impossible potted/sealed :(
So how do you know it's the PCM or a wiring problem? Did you check resistance of the wire from O2 connector to PCM? I suspect it is the PCM driver but did not see that you verified wire integrity.
Checking the resistance of the wire (unloaded circuit) is exactly what will get you in trouble...not a valid wiring integrity check, unless the wire is basically an open circuit!
Not a valid check yes but good if you know what to look for. The purpose was to check for a shorted wire to common. May not be worth the effort but then again only takes five seconds.
Don't know if it's physically possible to get into these units nowadays, but back in the 90's I regularly repaired, mostly racing ECUs. Not that hard, really, just look for the component which has blown a chunck out of its case. :D If I lived in the US, I'd have a crack at repairing those troublesome TIPM units... it irks me you guys have to swap those out just because of a bad connection/transistor/relay. I mean, you'd still need to swap them, but it would be for a refurbished unit at a fraction of the cost of a new one. I don't buy 'not servicable' until I've inspected such a unit for myself. Might even be worth reverse engineering the circuit boards and build new ones with beefier components.
I don't think I'd condemn the PCM just yet. It would be best to check all powers and grounds at the PCM first. Yes, the downstream sensor works properly, but it's likely that its circuitry is intentionally separate inside the PCM because the downstream sensor is mainly just there to monitor catalytic converter performance and function as an emergency back-up if the upstream sensor fails.
very interesting. the only thing i will add is this- the computer feeding the o2's instead of grounding it appears as if it cannot feed both voltage and amperage which probably is the computer however since it is feeding the juice i would want to test the power and grounds going into the computer since it probably has multiple feeds and one feed may be good allowing it to run but another may be bad. perhaps one is feeding the upstream and another power input is feeding the downstream. without a pcm schematic you'd never know. with multiple power feeds certainly they are split inside just how who knows.
Good point. However just by looking at the wiring diagram, one of 4 missing main power feeds would result in more issues than just one bad power feed to one oxygen sensor heater :)
I'll put this here also. that's funny, after finally watch the whole video, I'm thinking the ECM has a shunt bridge/resistor fault inside and it's folding-back thinking there's a shorted wire/sensor in an attempt to protect itself. would have been interesting to check the original O2 sensor for issues, do you know if it had a shorted heater or wire issue?
I'm not sure that using the PCM to drive those heaters is a good idea. I suspect corner cutting and money saving on behalf of FCA. They only expect those cars to last 6 years. IMHO.
opl500 - less than 1/2A is not "serious" current, What is unusual is that the PCM is SUPPLYING (not "sinking"). PN junction devices are much more expensive than NP device and some people say less reliable.
Some others have them in the front wheel wells; Corvettes had them there at one time, not sure if they are still in the wheel well now but earlier models were located there for certain.
I think you and EricO must have your brains studied. Smart cookies the both of you. Great video. Question.... What in your opinion is a quality oil filter?
craigsclocks The old adage, you get what you pay for, usually applies. My opinion, wic, Donaldson and Amsol. I’d stay away from box store filters, although some sell brand specific filters. There’s always better than the recommended filters
Pine Hollow Auto Diagnostics OEM are what is recommended by the builder of the vehicle, keeping in mind, it’s not in their interest for your car to last longer. I guess if you’re in the rust belt, probably makes no difference. All my vehicles are between 16 and 20 years old, with no rust! I’ve never had a corolla go less than 300k, and with minimal maintenance.
Well, now you're making my job hard lol, as I still have P0135 heater problem!! That's complicated job to find the root of my blazer issue!! Aggggh!! Lol. Wish you could find it in my blazer lol
@@NewLevelAuto haha, I would absolutely love to, Keith! But I live in Idaho :/ driving cross country which I would love to. But not feasible option for me at the moment :(
If the computer is doing the switching odds are good it's ground side switched. Driving a MOSFET on the high side is ANNOYING. They'll only do it if they have no other choice.
The one thing that will make you better at what you do, is always ask why. Curiosity is your friend. Don't ever change.
So at about 20 mins, you actually said it.. The PCM has the ability to put out voltage, but no amps. And this is the biggest problem with Chrysler computers that have power switched accessories. ( not sure if this is true about those that use TIPM) If the original o2 heater power circuit shorted, the computer driver gets smoked. Chrysler does not protect its power switched outputs via fuses in almost all cases, and if they do, it's usually over fused ( the fuse is too big). They haven't done so since the SBEC/SMEC days! ( in those days, shorted injector, shorted ASD relay etc, bye bye PCM) You nailed it. Sometimes it's a hard pill to swallow, so we keep trying to prove what we already know...
At Ivan, you're probably too young to have ever worked on 1, but the old Chrysler M body cars with the ESC computers were notorious for blowing computers due to shorted solenoids like EGR and purge. They would get full of condensation and short. The computer would go into a limp in fixed fuel and ign timing strategy , so the car would run, but have low power and really bad mileage. Techs would replace the ESC and it would work for about a day, then same scenario. Because these cars (81-89) never had a check engine light, techs that didn't have the plug in Chrysler scan tool, which connected at the ESC, could never check why the ESC failed much less read codes. They were a nightmare in the independent garage field. Unless a tech started poking around at various sensors and actuators, he'd never find what killed the ESC. The ESC was not protected at all except for main power inputs via fuse links. Back in the mid 90s, people would bring their cars to me and I got dubbed 'Mr. Chrysler'. Top things that killed the computers were shorted 02 sensors, EGR sols, purge sols, and carb throttle stop switches, all controlled by the ESC, none protected by a fuse. A little retro for ya!
Ivan, most techs would not go through the trouble you just did that's what makes you a good tech thank you for sharing.
I figured it was time well spent since we can all learn from this case study, and then make our diagnostic approach that much quicker and accurate :)
I think I know the secret. You must become sleep deprived to understand the inner workings of the computer-controlled motor vehicle. I mean how else can Keith get through 20-30 vehicles a day.
Good diagnosis Ivan. Without knowing the theory of operation you worked it out to be able to call a bad driver in the PCM. Thumbs up man
Keith didn't get that way overnight. I'm sure he had to work at it.
Many years of non stop diagnostic challenges
Absolutely. He just makes it look so easy and natural.
I can imagine. And they ain't gonna stop with a computer control for nearly every system and upgrades in tech every year.
Experience does that. Try explaining to an end customer they are paying for your experience not time though and watch their head explode when you diagnose it in 10 minutes and still expect the full invoice amount.
I don't know, but I think Keith solely works for other shops when they get stuck on something rather than having to deal with the irrationality of general public customers. Wise man. That's not a sleight on the customers BTW, we're all irrational idiot customers when we get outside our sphere of knowledge and it all becomes mumbo jumbo and unicorn farts as someone tries to bill a gadzillion bucks for apparently just standing and thinking for a while :D
And this lady's and gentlemen is what separates the Mechanics from the Technicians !!! 😏💪
i really like your diagnosis,i feel for you spending the time to solve the problem
You answer your own question. Then question your own answer. That's why Keith can go through so many diags. You are great at what you do brother. Be more decisive. Trust yourself. We are reverse engineers. Clearly the original engineers didn't get it all right. So we aren't either.
"Okay, we have 12 volts and....uh....this" lol Love that response Ivan! Great lessons here. Thanks.!
I always acquire knowledge watching your videos Thanks for your time
My pleasure! Are you related to Bill Nye the Science Guy? Love his show :)
Ivan,
Great video and brilliant diagnosis! I always learn when I watch your videos - thank you!!
God bless
Paul
4:55 here, The Incredible Ivan, thanks Ivan. Love your videos. Looks like I'm not the only one who cant sleep. Damn back is shot.
Back problems are the worst. Hope you can find a good chiropractor!
Lovely place to locate the PCM. Keeps it cool I guess... water cooled!
Nothing new though. Used to own a Mk3 VW Golf or Rabbit as you may know it (1996 era). The ECM for that was located in the gutter at the bottom of the windscreen. When you read "access the ECM by removing front wipers and plastic rain gutter trim" you have to double check it's not 1st April.
That said. Never had any issues with it to be fair.
Wow! What an awesome video on something so simple and yet so complicated at the same time. Great job.
Sometimes the simple things on the surface turn out to be the real head scratchers, and visa versa!
true true what you said at the end at bonus footage,well done Ivan..
damn these Chrysler cars lol loved the bonus footage tho!
I think I do 20-30 vehicles too ... per YEAR!! 🤣
This is one of those cars that would've had my blood boiling. Guaranteed it would've taken me 12 hours to be absolutely certain the PCM was at fault. My main problem is I get so frustrated, the last thing I want to do is experiment on good circuits. The only cure for that in my case is to troubleshoot American cars built before 1981. 😁
I hear you on the engineering! Both my '86 Grand Marquis AND my '93 Volvo 940 have the ECU in the right side passenger footwell. Only seems logical to keep a COMPUTER out of the weather and road salt! Every year these vehicles amaze me. I don't know how anyone in auto manufacturing can sleep at night. It's all about $$$$ today ...
Nice job being patient with this one! 👍
that's more reasonable for the junk that's out now days, I hate working on the stuff, so I don't ;)
I don't blame you one bit!!
I enjoy following your logic to the end.
Thanks Wyatt! I try to make the logic train continuous and understandable :)
Just for the fun of it, I would have applied 12 to the upstream heater and checked if car went into closed loop. And O2 performance normal. Great analysis. Fun.
Ooh, great idea!
That would be a cool "bypass test" :)
or swap the upstream/downstream o2 heater wires, would be close enough. or parallel them to see if smoke emits fromt he other driver/ecm :))
Will this still cause a code if one was to supply its own 12v to the brown tan heater wire to the upstream sensor?
good job.... making a pcm call is checking... good thinking on the pcm droping out the heater for for a high low circuit
As soon as you were able to instantly pull down the upstream heater output with the testlight it was clear the output on the ECM was pooched, regardless of the O2 sensor heater being open circuit/connected or not. Otherwise it would take an appreciable/measurable length of time for the ECM to stop trying. That's just the way input/output stuff is programmed. Outside of racing I'm sure the delay for determining an input to be valid is about 0.3s, a blink of an eye for us humans, but an eternity for digital logic. Connecting the test light just immediately influenced the output, hence the output was pooched.
Thank you Ivan. Good job. I appreciate your videos.
Literally had the same issue Monday on a 2500 ram. Replacing computer fixed it.
Awesome casestudy...thanks!
outstanding troubleshooting!
thank you Ivan for sharing , I have not got into those too deep, how ever I remember a 04 pt cruiser that went to the shop with up stream and down stream o2 heather codes , both new sensor , it was not my vehicle it was working other technician ,I told him to use ntk per Scanner Danner video on this case study, this tech told me 02 sensor is 02 does not matter he did his test and conclude to replace both 02 sensor with different brand but still not ntk, guess what both codes returned, they told the customer is computer so in about 4 month it comeback for emission test, they gave me that to me , for diag I recommended with out doing any test at this time ntk both 02 sensor , the service writer told me those sensor are new and I said I can diagnosis computer issues after I get oem sensor only. and attempt to run monitors I installed the 2 sensor and clear the codes , by the way it had transmission codes before the first time they installed different brand 02 and now , I clear codes run all monitors next day in the morning all run no codes present on any computer , next oil change in about 3 month I check for monitors and codes and was clean.
at this time I played with some scope test, I realized on the ground side for the o2 sensor they send 2.5 v they call it floating ground , yellow lead on signal wire. if you connect your scope and connect black lead ground on battery it swing from 2.5 to 3.5 volts, now connect the ground to sensor ground and it swing from 0 to 1v as normal o2 , any way that is how far I get , reality is those NG Chrysler computer like ntk only probably the sensor has some compensating for floating ground or who knows . the previous set of o2 sensor were denso and second set were bosh.
it pass smog now , I get weird diag sme times with people force to do keep the vehicle on the road to registrar , smog license bring me more fun diag.
thanks once again
Great story, Joel. Yes, with any engine electronic components OEM is the only sure way to go. Good for you for being persistent!
I had a question for you, it's good or bad to add more grounds on the engine bay or engine in Chrysler Vehicles?
Could have tested at the relay instead of digging out the connector probably a reason you lose some time. Could have been shorted relay as well!
great video
bonus .... quick tip tuesday on friday a piece of heat shrink on about 90% of the test light metal tip will keep down on arcing to ground no welding allowed while testing lol
Love the tip!
no problem ivan , hope that helps someone else out there as well ...
you did give me a great webpage to get wiring diagrams from ( bbbind.com ) so just throwing one back your way
thanks for your hard work ivan.
This one must have been for the master techs. If you could do a companion video to explain what you did and why, that would be great.
Well, in essence the O2 sensor heater is a power-side switched device driven by the computer. Computer can't provide the power so it's broken haha
Great video Ivan, I was wondering , the Heater Duty cycle is controlled indirectly by the Engine temperature. You didn't mention about a possible ECT failure, but I guess if there was an ECT failure , the code would have popped up and also the rear O2 would have had problems with the heater circuit. Thanks again.
if I was in doubt, I'd repeat the same test on a working O2 sensor/bank.
also a simple resistance test of the heater itself, compare with other bank or see if you can find known value for it. other than most being 5 to 10 ohms :)
Nice bonus footage!
Not that it matters (because this is still internal to the PCM) but the wave form you are showing at 23:41 is a classic "current limit/fold back" wave. It seems like the current limiting circuit is actually "blocking" the signal from the CPU. This make sense, because the data say the software has it turned on 100%.
So why is it limiting the current when it's not supposed to?
Not sure exactly why, but that big spike is triggering the current limiting circuitry in the driver.
yeah looks very much like driver issue . Testing the next era of motor cars will be fun with more computer strategy, bias voltages, dual side controls and so forth :-S
This one potentially easy with basic test procedures, never easy calling pcm though unless real clear cut evidence .
Got to love under hood pcm locations and this front wheel well takes the biscuit lol, the must want early failures and bigger expense in light front end collisions .
Can't see how Keith can do over 20 cars in a day, if give each car 30 minutes plus mobile commute time you hitting close to 12hrs . I don't do more than 12 cars and that from a shop which far less downtime over mobile, sure some things take 5 minutes but most are 30 minutes to a good hour .
The voltage without amps on upstream O2 might have been the voltage driving the power transistor / mosfet, leaking to the output. If there is no voltage or the transistor / mosfet has failed and does not turn on, you might see just the driver stage signal, which can put out only a few milliamps, enough to turn on the driver transistor / mosfet. Any load will pull it down.
Same thing when the power transistors fail in audio amplifier, you might hear a very low volume sound, it is the driver stage.
Just to avoid confusion in the analogy in audio whet we call the output stage is what the pcm calls the driver stage. We could have easily gone for the same terminology but NOOOOO! 😂
I think this hypothesis is very likely :)
Did you make the test lights? If so, could you show us how to make them?
What if you shirted the downstream o2 heater control to upstream and cut the upstream orgianl control wire to resistor to ground(make it belive all is ok), would it have then working o2 on upstream too? ...Or would it have bean too much for the downstream driver to handel?
What are you seeing Ivan on your Scope is the MCU signal to the MOSFETs Gate, this is a typical sign of a Transistor failure, being unable to carry load though its electro-Chemical bridge is just like having a weak/shorted electro-mechanical relay unable to latch
Awesome! Thank you for the info!
When you showed the test light killing the drive i wondered if the manufacturer was using a heater with a higher resistance, just to be a pain in the arse!!. (Special part).
The downstream one seemed ok with a test light, but the plug is different, perhaps trying to stop you swapping sensors maybe.
I'm sure you found out the truth, so don't forget to leave us on a cliff hanger Ha ha :-D
Well the upsream heater resistance was 4 Ohms so that sucker can draw 3 amps at full power!
Still makes me question powers and grounds on the PCM if it was unable to light the test light. Like Ivan said, you'd think that the upstream and down would be on the same connector and pwr/gnd but maybe not. I'd hate to throw a PCM at it and still have the issue.
Good point, but would expect the car to have many more issues with a bad main power/ground at the PCM.
Was there corrosion on the PCM connectors?
seems having the test light on the sensor wires is more or less shorting it, making the ECM think it's shorted or stuck O2 and seems to be turning the heater off,.
would have been nice to see the light each time it started, to see if it powered it on or not when it briefly claimed 100%. thinking it was lighting and going off before you got out to see it, if I'm inside a vehicle, I put the test lights up on the windshield so there's no missing it. been burnt too many times that way :)
damnit, posted too soon in the video again :))) still wondering if it sense no or shorted O2 and doesn't try to turn on the heater.. nothing surprises me with crapslers.
Love Bonus footage.....Kieth must be getting rich, sometimes people get lucky and hit on the trade they were meant for, and totally fly past anyone else in that field, and yes get rich. Or at least afford a swimming pool.
OK, was it the pcm. was the PCM replaced? Was you diagnosis correct?
Yes it was. And I programmed the new module and retested all ok
WHEW now I can sleep at night :D
@NewLevelAuto is this true? Can this cause the heater circuit driver on the computer to go bad? "If this all looks good, we will need to see if
the ASD control circuit has voltage on it
with the key off. When there is a voltage on
this circuit, it will damage the PCMs heater
monitoring resistor in the PCM. We will
need to check the brown/gray wire at the
asd relay for voltage with the key off and if
there is voltage with the key off it will
damage the PCM."
Up Date on my Tacoma problem....I Fixed it, in the end it was the Dist, apparently the Signal Generator was starting to go
bad and was not sending a signal to the ECU that the plug had been fired, so the ECU would cut fuel and spark
and a split sec later it would send signal again, so I was getting a bumping feeling going down the road.
But Hey I fixed something The Toyota Master Techs, could not find, only took me a month :)
New OEM Dist from Toyota was 550.00 Ouch. But the little Tacoma with 257,000 miles is humming down the road
again. Yea
Sweet! The igniter on my old Mazda MPV has a habit of burning up every 100k miles or so. Distributors are $300 a pop on eBay :)
I saw them on EBAY for anywhere from 99 to 250, but I could not trust them. This took me to the
very end of my troubleshooting ability, But I learned a whole lot about my Toyota, and in troubleshooting
in general. In the end I learned you have to understand how all these electrical parts work together, because if you dont, you end up chasing your tail. It was not a easy problem to find. But because of the Videos you and Eric have posted through the years, I knew I could figure it out. Dont get upset, get educated .
This kind of head scratching drama makes a simpleton like me want to just own and ride a bicycle. Cheaper on insurance too. Maybe on to something since I am retired.
If I did that, I could've bought my first house at 17! Would be a millionaire by now, too ... 😫
haha I have 4 very reliable bicycles and 2 reliable motorcycles, just in case one of my 3 mostly reliable cars lets me down xD
Get an early 90s Acura, sink a couple/3k into it (more that it's worth but who cares) and just drive.
Both my '86 Grand Marquis & '93 Volvo 940 are pretty hands off as far as repairs go. Neither one gives me any grief, unlike my '07 Silverado - always something new with that one. Been driving around MA with a "R" on the windshield, since the stupid monitors haven't run in 2 years! Who knows why ... and I don't have the patience to find out! As long as it starts and runs when I need to tow something, I'm good. :)
What a pos location for the pcm. I thought you were joking for a second but there it is.
Hey guy;
Tom here, A voice from a while ago.
I have been out of commission for a bit and am back on the 1999 Dodge Durango no buss. The code that shows up when I hooked up the new scanner is P 1687. I'm still worried that it might be a wire issue. I have been trying to test wires for shorts and am overwhelmed. Any direction you could send my way?
No one can deny that you're persistent.
P.S. What are you doing posting videos at 5:55 a.m. ?
When do you (and Eric O. at South Main Auto) finally go to sleep?
LOL! I think Keith D. beats us all in the "lack of sleep" category haha
I've got you all beat in the SLEEP category - 10 hours last night, and I could've went a couple more if I didn't have so much to do today. 😁 I'm the polar opposite.
I'm going through a very similar issue can anybody please help me? Have a 2005 pacifica 3.5L same location of computer on this video so same vehicle basically. Code is p0131 heater circuit low voltage, o2 sensor is a brand new denso and code still pops up. Just replaced the ecm through ebay with vin programmed and I still get this code. Please help I heard something about the fuse box being an issue or something. I get good ground at my 02 connector but no 12v. Thanks.
Awesome video 👍🏻👍🏻
I think Keith see the Matrix in his head.
🤪
Around 26 minute mark I was thinking could you make a DIY box that would drive the sensor externally? You have pulse, but no width, so no.
excellent video
S.I. doesn't disappoint. I just want to know what jack leg ran all the wires overhead.
HAHAHA! I noticed that too - they didn't even cut the zip ties they threw up there! Someone wasn't getting paid enough to deal with all that. 😁
My attitude would probably be the same after spending 20 SECONDS in that traffic down there ... 🤣
Hey now fellas , that was me 😂
I had a similar situation on my dodge that ended up being pin fitment of the PCM connectors. There are no test points on the PCM board to tell how well the signal is getting onto and off of the board (so the factory basically considers the PCM and its wiring harness to be ONE part [which is a PITA to change]) so I'd really caution anyone working on a modern Mopar to do the drag test with a appropriately sized pin (probably .055" on these) on the connectors
Hi Ivan you gonna be at TST in pa in oct?
Good question. I will check!
I'd have been cranky early in and shorted the heater wire to ground too see if the ECM said "shorted to ground/low" or nothing. as it should detect when key is flipped on and not try to power on "hard/full" anymore.
then again I hate the garbage in vehicles and still prefer smoke clouds to find the issue :)))
Proper code would set most likely. The voltage sensing circuit still works :) Then what?
I'm not sure it would have thinking/guessing in terms of the ecm internals, then again I could be off target on it's design and it may still sense it proper, so if you get one you're sure is bad again, try shorting it to ground! for me/us/the world :)
it would have been great if they had the original O2's for you to test and look for physical damage, like did it have an intermittent short to ground and the ecm slowly cooked, in theory it should detect that and set code, but we all know how codes "always set and are right" HAH!!!
it would be neat if someone could tear into bad ecm with same issue, but I suppose it's near impossible potted/sealed :(
So how do you know it's the PCM or a wiring problem? Did you check resistance of the wire from O2 connector to PCM? I suspect it is the PCM driver but did not see that you verified wire integrity.
Gene Mean testing the control wire at the pcm connector...
Checking the resistance of the wire (unloaded circuit) is exactly what will get you in trouble...not a valid wiring integrity check, unless the wire is basically an open circuit!
Not a valid check yes but good if you know what to look for. The purpose was to check for a shorted wire to common. May not be worth the effort but then again only takes five seconds.
Like I told Eric o. , those fca's really keep you busy.
Ivan, how's that lady's toyota corolla a/c compressor still working ? let me know man
Haven;t heard from her so I assume it's fine :)
So you went in and resoldered/replaced the heater driver device in the pcm? LOL
You can bet if it was Ivan's car, he would have.
🙄
Don't know if it's physically possible to get into these units nowadays, but back in the 90's I regularly repaired, mostly racing ECUs. Not that hard, really, just look for the component which has blown a chunck out of its case. :D
If I lived in the US, I'd have a crack at repairing those troublesome TIPM units... it irks me you guys have to swap those out just because of a bad connection/transistor/relay. I mean, you'd still need to swap them, but it would be for a refurbished unit at a fraction of the cost of a new one. I don't buy 'not servicable' until I've inspected such a unit for myself. Might even be worth reverse engineering the circuit boards and build new ones with beefier components.
I think some DIYers actually bring the troublesome fuel pump relay out of the TIPM and wire it up separately :)
Always look for the "crispy critters" when troubleshooting a board. Sometimes you can smell them.
I don't think I'd condemn the PCM just yet. It would be best to check all powers and grounds at the PCM first. Yes, the downstream sensor works properly, but it's likely that its circuitry is intentionally separate inside the PCM because the downstream sensor is mainly just there to monitor catalytic converter performance and function as an emergency back-up if the upstream sensor fails.
anything is possible I guess. That would be the next step to be 200% sure :)
Good vid Ivan. One observation. Can you not use the Virus wirelessly to stop keep going back and forth?
Thanks James, sometimes I forget it is wireless haha
Great video ivan
Thanks Chris! Hopefully the thought process wasn't too drawn out lol
Never give up!!!
LOL that's my motto!
very interesting. the only thing i will add is this- the computer feeding the o2's instead of grounding it appears as if it cannot feed both voltage and amperage which probably is the computer however since it is feeding the juice i would want to test the power and grounds going into the computer since it probably has multiple feeds and one feed may be good allowing it to run but another may be bad. perhaps one is feeding the upstream and another power input is feeding the downstream. without a pcm schematic you'd never know. with multiple power feeds certainly they are split inside just how who knows.
I was expecting Ivan to show us those too. I assume he checked and both oxygen sensors are supplied by the same power and ground.
its never safe to "assume" finding those feeds then isolaitng one at a time would be the way to find out
I'm not assuming that they feed from the same place, I'm assuming Ivan checked where they feed on the wiring diagram.
Good point. However just by looking at the wiring diagram, one of 4 missing main power feeds would result in more issues than just one bad power feed to one oxygen sensor heater :)
I'll put this here also.
that's funny, after finally watch the whole video, I'm thinking the ECM has a shunt bridge/resistor fault inside and it's folding-back thinking there's a shorted wire/sensor in an attempt to protect itself.
would have been interesting to check the original O2 sensor for issues, do you know if it had a shorted heater or wire issue?
So.....what was the final outcome?
PCM?
yup ;)
@@PineHollowAutoDiagnostics
Cool!
Nice weak driver diag! New scriber checkin in from sma...good stuff here...
Welcome!
I'm not sure that using the PCM to drive those heaters is a good idea. I suspect corner cutting and money saving on behalf of FCA. They only expect those cars to last 6 years. IMHO.
The way they build stuff today, it's amazing they make it out of warranty ...
LOL!
Most PCMs control the heater circuit, but they use ground side switched "drivers" and possible even a relay.
Anything that draws serious current, needs to be off the board traces and on a relay, IMHO.
opl500 - less than 1/2A is not "serious" current, What is unusual is that the PCM is SUPPLYING (not "sinking"). PN junction devices are much more expensive than NP device and some people say less reliable.
i would say that road salt doomed that PCM.
PCM in the wheel well? Seriously?
Some others have them in the front wheel wells; Corvettes had them there at one time, not sure if they are still in the wheel well now but earlier models were located there for certain.
Just another friendly reminder: the scanner is wireless 😬
HAHA old habits die hard!!
Brilliant
pin fitment @ PCM???
Look/see what the voltage and current of the downstream one for comparison .. aha that’s what you did .. heater ckt upstream “has no beans”
I'm feeling your pain
And it isn't like Michigan doesn't have the same road salt and snow either. They know better.
I think you and EricO must have your brains studied. Smart cookies the both of you. Great video. Question.... What in your opinion is a quality oil filter?
craigsclocks The old adage, you get what you pay for, usually applies. My opinion, wic, Donaldson and Amsol. I’d stay away from box store filters, although some sell brand specific filters. There’s always better than the recommended filters
OEM!
Pine Hollow Auto Diagnostics OEM are what is recommended by the builder of the vehicle, keeping in mind, it’s not in their interest for your car to last longer. I guess if you’re in the rust belt, probably makes no difference. All my vehicles are between 16 and 20 years old, with no rust! I’ve never had a corolla go less than 300k, and with minimal maintenance.
Yeah maintaining old cars is a chore in the rust belt that is for sure!
Misusing a test light as a pulldown resistor, lol.
Well, now you're making my job hard lol, as I still have P0135 heater problem!! That's complicated job to find the root of my blazer issue!! Aggggh!! Lol. Wish you could find it in my blazer lol
Send it on over 😁
@@NewLevelAuto haha, I would absolutely love to, Keith! But I live in Idaho :/ driving cross country which I would love to. But not feasible option for me at the moment :(
Idaho? I love Idaho. Maybe another PHAD road trip is in order ;)
@@PineHollowAutoDiagnostics hell yes!!!! That would be fun! Would love to see ya :)
I have to remind myself constantly to keep it simple stupid. That being said I have been in that exact situation condemning a computer :)
I hate making the call on a module, but that's why they call in the mobile diagnostic techs lol
Whoa
Not 1st BOOM haha
Almost!
O2 sensor showes it's feminin side , it lost it's rationality lol
meh, plug/harness or ecm lol with it being Crapsler, probably all three at once :))
Hi at work
If the computer is doing the switching odds are good it's ground side switched. Driving a MOSFET on the high side is ANNOYING. They'll only do it if they have no other choice.
This is Chrysler, annoying is just what they do.
Crapsler ;)
Burn the PCM man🚗😂
does not work ntk must be used
Just another in the many reasons not to buy anything from Chrysler
Chrysler junk 🤦♂️
First?
Yup you got it!