Determining Circuit Design (Power or Ground Side Switching)

The full version of this case study will be available on ScannerDanner Premium on 5-2-2019. In this clip I will be talking about the following:
You cannot properly troubleshoot a circuit problem without first knowing the circuit design!
Does polarity of an inductive amp probe matter?
How to identify a power and ground side switched circuit without a wiring diagram and pulse width modulated (PWM) controls.
Here is the full video breakdown:
Jeep Liberty PWM O2 Heater Circuit Testing (New Oxygen Sensor Installed)
Video Breakdown:
00:24 - 2006 Jeep Liberty P0158 O2 Sensor 2/2 Circuit High
01:16 - using O2 bias voltage to check heater circuit operation
03:20 - O2 PWM command on scan data
05:18 - testing begins under the car, O2 locations
06:21 - using sensor side colors to ID the heater circuit
07:04 - the working side (B1S2) O2 heater amperage waveform
07:31 - 2005 Dodge Ram 1500 O2 Heater Code (Faulty PCM driver) and Stalling Conditions
Part 1 tinyurl.com/y52j7v3e
Part 2 tinyurl.com/y5qqwjqb
08:00 - the bad side (B2S2) O2 heater amperage waveform
10:14 - voltage measurements and how to identify power or ground side switching
15:30 - voltage measurements of the 2/2 sensor begin
16:22 - low voltage and amperage found (possible "smart" driver using "intentional shut down")
17;30 - using a test light to substitute the heater circuit
19:44 - test light not lit, with good commands, suspect wiring or PCM problem
20:05 - wiggling test light ground with 100% command (no light)
20:55 - measuring the good side (1/2 sensor) again (relocated test light ground)
22:40 - connecting the 1/2 harness into the 2/2 sensor
24:20 - resistance measurement of the heater circuits 1/2 = 4.88 ohms 2/2 = 6.08 ohms
28:17 - amperage and voltage measurements of the 2/2 sensor using 1/2 control (test light installed the entire time)
30:25 - I proved nothing :-)
30:53 - recheck of the 2/2 heater
35:05 - testing begins under-hood
37:00 - wiring diagram and wire location at the PCM
37:40 - 2/2 circuit voltage at the PCM
39:40 - 2/2 circuit amperage measurement to confirm wiring integrity
40:20 - why a power side switched voltage waveform can be misleading
44:09 - scan data O2 Bias and heater commands look bad for the 2/2 sensor
45:20 - starting to question the sensor again
46:25 - WARNING! Aftermarket Oxygen Sensors (Chrysler)
Part 1 • WARNING! Aftermarket O...
Part 2 • WARNING! Aftermarket O...
47:40 - voltage and amperage waveforms after running (compare to 37:40 mark)
48:30 - 1/2 voltage and current
49:30 - surprised by what the test light does when added to the circuit (both scope and scan data)
53:15 - why couldn't we do these tests under the car!
55:30 - 1/2 harness plugged into the 2/2 sensor to prove wiring is fine (scan data heater commands)
57:30 - test light affect on the circuit (bias and heater command)
1:01:30 - new oxygen sensors installed, scan data readings
1:05:22 - final discussion with my son Caleb discussing why the test light tests failed under the car
ScannerDanner Tools:
www.scannerdanner.com/tools.html
www.amazon.com/shop/scannerda...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdanner.com/join-sc... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!

[@billyyoder8171]

Thank you Paul. Good job. Have a blessed and safe week. I appreciate your videos.

[@MitchellHenderson1980]

You are by far the best online teacher on the web... Love your videos, love your methods, you are a absolute must in any shop I work in for my new techs..

[@ScannerDanner]

That's what I'm starting to hear which is awesome! Just had a guy buy three subscriptions for his techs and he's going to give them a $100 bonus for any tests they pass. (I provide access to my test bank for anyone with a gmail account) I think it's a great idea! Gets these fundamentals burned into their brains right? Thanks so much for your kind words and encouragement.

[@wyattoneable]

You know I'll be there! Always a pleasure to learn from you Paul.

[@andrewk778]

Always look forward to your videos. I bought your book ages ago. It is an indispensable training/reference tool. Thank you for sharing.

[@amadoterte1714]

Hi Mr Paul Danner. Your ideas about the power side switching and ground side switching applications in automotive electrical systems helped me so much in DIY troubleshooting of my own diesel truck. Thank you very much, sir.

[@ScannerDanner]

heck yeah man, awesome! Thank you so much and I'm glad this helped

[@josealers67]

This keeps on getting better. Love the questions and answers. Great job guys. See you on SD Premium.

[@parochial2356]

Agree - 100%

[@Az2FL]

Your book and videos are gold! They have helped me ace my A8 and A6 tests! Thanks a ton for all the info and time you put into your videos.

[@ricardiagnostics]

Really love your videos mate, but recently been way too busy to keep going watching but every now and again I just stop by either here or on website or Facebook, cracking job mate all the best

[@parochial2356]

Paul; you're 1 heck of teacher. 5 - stars!

[@calimesacox]

Thanks brother.. always appreciated. Any info drop from you is a big help for me.

[@theadventuresofjavier8698]

Watching while my daughter has choir practice. God bless you Paul. Btw i was in Ohio last week working on a friends honda pilot.he flew me in to do the timing belt, spark plugs and front wheel bearings...good golly the rust is no joke. Pb blaster and a big hammer was my best friend. You poor techs back east are in my prayers. 🙏

[@jahrain1693]

Thanks a lot I never knew we have PWM heater circuit.am learning more and spreading my wings.i have understood diagnosis through your channel and I don't know what I will become if I get money to pay for ur paid channel but I have bought ur Ebook and chewing and reading every second.i will become like u one day in my country.i wil be the hottest diagnostician in Ghana the moment am able to buy a oscilloscope and I will pay for ur channel and learn more....Thanks

[@vincescalise4821]

rusty ass frame in Pennsylvania sounds like ever vehicle I have ever had LOL , great video aiways tons of information thankyou ,and cameraman Caleb does a great job.

[@weldingjunkie]

Great video Paul. I really need to buy your paper book on AES. Always look Foward to checking out your videos. Thanks brother! ... Jay

[@SmittySmithsonite]

This is gonna be a great vid, I can tell already! 👍👍

[@mohammedcherifi9206]

Thank you Paul for your efforts and a good thank to caleb too

[@tigerksewsankar7667]

Love all your videos paul thank you ..

[@koltencanfield135]

Awesome edits. Think you may have another premium member coming your way👌

[@ScannerDanner]

You won't be disappointed, ask around, read my feedback page of my website. Thank you! Hope to hear from you in the comments of the premium videos.

[@Pablo_Automotive]

Great job again Paul and Caleb thanks forma share a hug from Spain 🔧👌👏☺

[@ScannerDanner]

Here is the full video breakdown: Jeep Liberty PWM O2 Heater Circuit Testing (New Oxygen Sensor Installed) Video Breakdown: 00:24 - 2006 Jeep Liberty P0158 O2 Sensor 2/2 Circuit High 01:16 - using O2 bias voltage to check heater circuit operation 03:20 - O2 PWM command on scan data 05:18 - testing begins under the car, O2 locations 06:21 - using sensor side colors to ID the heater circuit 07:04 - the working side (B1S2) O2 heater amperage waveform 07:31 - 2005 Dodge Ram 1500 O2 Heater Code (Faulty PCM driver) and Stalling Conditions Part 1 tinyurl.com/y52j7v3e Part 2 tinyurl.com/y5qqwjqb 08:00 - the bad side (B2S2) O2 heater amperage waveform 10:14 - voltage measurements and how to identify power or ground side switching 15:30 - voltage measurements of the 2/2 sensor begin 16:22 - low voltage and amperage found (possible "smart" driver using "intentional shut down") 17;30 - using a test light to substitute the heater circuit 19:44 - test light not lit, with good commands, suspect wiring or PCM problem 20:05 - wiggling test light ground with 100% command (no light) 20:55 - measuring the good side (1/2 sensor) again (relocated test light ground) 22:40 - connecting the 1/2 harness into the 2/2 sensor 24:20 - resistance measurement of the heater circuits 1/2 = 4.88 ohms 2/2 = 6.08 ohms 28:17 - amperage and voltage measurements of the 2/2 sensor using 1/2 control (test light installed the entire time) 30:25 - I proved nothing :-) 30:53 - recheck of the 2/2 heater 35:05 - testing begins under-hood 37:00 - wiring diagram and wire location at the PCM 37:40 - 2/2 circuit voltage at the PCM 39:40 - 2/2 circuit amperage measurement to confirm wiring integrity 40:20 - why a power side switched voltage waveform can be misleading 44:09 - scan data O2 Bias and heater commands look bad for the 2/2 sensor 45:20 - starting to question the sensor again 46:25 - WARNING! Aftermarket Oxygen Sensors (Chrysler) Part 1 kzbin.info/www/bejne/Y524ioWnlr6pj6s Part 2 kzbin.info/www/bejne/naW3fIKrqpt4htk 47:40 - voltage and amperage waveforms after running (compare to 37:40 mark) 48:30 - 1/2 voltage and current 49:30 - surprised by what the test light does when added to the circuit (both scope and scan data) 53:15 - why couldn't we do these tests under the car! 55:30 - 1/2 harness plugged into the 2/2 sensor to prove wiring is fine (scan data heater commands) 57:30 - test light affect on the circuit (bias and heater command) 1:01:30 - new oxygen sensors installed, scan data readings 1:05:22 - final discussion with my son Caleb discussing why the test light tests failed under the car

[@exmotorsports]

Oh dang...Looks to be a very interesting video.!

[@blockbertus]

Hey Paul, please check the URLs to part 1 (both). Somehow the "Part" after each URL is contained in the URL itself and therefor breaking the URL.

[@ScannerDanner]

Thanks! Should be good now

[@billyyoder8171]

Thank you Caleb for helping your Dad. Good job. Bless you and your family.

[@lawsautomotive108]

Good video Paul.

[@coreysuttles1362]

Man you really favor the ice man chuck Ladelle 🤘💪💪 great video

[@fire7765]

Great job, thx for sharing.

[@alexmessina7652]

Nice. Thanks! Here’s one. What would u make of a heater with constant V on feed 0v on grnd KOER, constant 1A current flow, ohms in spec (10-13). No codes. Complaint is higher than expected fuel use on city driving. Acceptable on long trips. I’m told some early thimble type O2 like this one use constant ‘on’ mode. Never encountered before this. Talking abt a 2004 Hyundai Accent 1.6lt Auto.??? No post cat o2. fuel trims v good.

[@throttlebottle5906]

easy as pie for many of us, but some people just don't know and need help :) them PWM circuits can be tricky to learn

[@evangelinasanchez2188]

great that you have your son and teach him to be a good man

[@phillloyd8625]

Thanks again Paul, say hi to your Mom again too 👍

[@jeremieparker5703]

Thank u Paul this gave me just a little bit more in-depth explaination as to reconizing pull up and pull down designs I don't own a scope yet but I have been following along just to grasp the basics for when I do finally cross that bridge... For the longest time I use say man... What in the hell is Paul talking about lol.. I get it now man I see my error I was confusing Duty cycle on and off time when I should have been looking at voltage spikes to determine if it is power or ground side switch... Bro you are awesome this quick video summed it up real nice for me thank you again I am humbled as I continue to learn your teachings God bless you brother

[@ScannerDanner]

Awesome Jeremie! These kind of stories are really what drives me. I love helping others man and to watch them succeed using methods I'm sharing is a very humbling experience. But all glory goes to God, who has given me my abilities and the gift of gab :-)

[@jeremieparker5703]

@@ScannerDanner ... God gets all the glory but I truly thank him for you bro u just don't know how I really look up to you man you are my big brother that let the little brother tag along...lol ... Thanks again Brother

[@ScannerDanner]

May God continue to bless your hands and your mind my brother

[@whitetiger8652]

Thanks Paul!

[@robertwelch3899]

Thank you Paul.

[@ekimbrough1413]

Damb Paul...I had a question for you about the voltage vs. current reading on the O-scope. This video answered my question I think. Since current is inversely proportionate to voltage...does the current rise on a measured 5v digital wave reflected as the high line while the voltage is reflected as the 0v event, being the inverse? And is this measurement reversed depending on whether the component is power sided or ground sided? Please re-affirm or clear my fog on this. Thanks Mr.P 😀

[@asadmehmmod5460]

Wonderful thank you

[@stevenkietzke5582]

Question Sir snap on is discontinuing the verus. Are you going with the Zeus? Great video thanks again

[@ScannerDanner]

not anytime soon, unless Snap-on sends me one lol but that won't happen

[@pantelis241]

Man I love you 🤗👍

[@ozzstars_cars]

Good stuff.

[@freeusnow6804]

Paul hows your mom doing.I HOPE SHE IS WELL THANK YOU VERY MUCH FOR INSTRUCTIONAL CONTENT.all ways a faster and smater way.

[@ScannerDanner]

She is in her second month of chemo and is doing well, thank you for asking!

[@Viper81766]

@@ScannerDanner Amen -:)

[@user-io3hw7hx7q]

Awesome thanks

[@OneSierra]

Thanks!

[@VoltageDropDiagnostics]

Great info. Your son is a lucky kid! Not many people get to apprentice under someone like you! Haha

[@johnaclark1]

Actually, between SDP and the YT channel it's almost the same as apprenticing under ScannerDanner. I wish I had him around to ask when I have a car mopping the floor with me but in the end I'm better for not being able to have that crutch. He's shared everything we need to know and it's served me quite well so far. I've got no formal training, other than SDP, and I've fixed a few cars in the last year that local shops couldn't figure out.

[@ScannerDanner]

@@johnaclark1 yeah man, that's what I'm talking about, thank you John!

[@mksalgado]

On your video of Toyota celica, what else may cause a weak spark besides the coil

[@ScannerDanner]

low voltage on the main power feed, a poor ground on the igniter, a bad igniter, a weak coil, a cap and or rotor problem if you are testing at a plug wire end

[@KY.0009]

Really helpful video! In your experience, how often have you come across O2 sensors that are 15-20+ years old and still fully functional? Do they all eventually become less accurate over time?

[@ScannerDanner]

they become contaminated and yes need to be replaced when their signal voltage and frequency start to deteriorate

[@curlymyhero]

Scanner Danner thx 4 the upload! I'm not a real mechanic (more of a hack) but in this case of a power-side O2 sensor and a poor ground on the ECU I'm assuming the trouble-code would b the 02 sensor side. Correct?

[@ScannerDanner]

not sure what you mean Brent, sorry

[@curlymyhero]

@@ScannerDanner Well I'm trying to locate a few of your video's on cars with bad grounds... On my car I'm now getting 11 v. back to negative but the car runs fine--just killing batteries... Thx

[@ScannerDanner]

@@curlymyhero here you go Brent, it is my ground circuit problems playlist (7 videos) kzbin.info/www/bejne/amXHgWmOaLaGa6M

[@metalhalide4043]

I have a Jeep 3.7 with a bad heater control driver, can the PCM be repaired?, if I do not replace the PCM is the only effect the engine will take longer to go into closed loop when cold or can it go into open loop when the engine is idling or low RPM at operating temp?

[@ScannerDanner]

you could send the PCM out to be repaired. Yes, the engine will not enter closed loop as efficiently as it should. Gas mileage will be affected and then you may also cause damage to the catalytic converter, especially during stop and go traffic driving.

[@metalhalide4043]

@@ScannerDanner Thanks, can you recommend someone that repairs them or sells reman PCMs?

[@jesusmartinez6237]

how much is your premium?

[@8power0]

HELLO MISTER DANNER , I HAVE BOUGHT YOUR BOOK ONLINE AND I WOULD LIKE TO HAVE IT ON THE JOB WITH OUT HAVING TO HAVE WIFI YOU HAD SAID WHEN I HAD BOUGHT THE BOOK THAT IT WAS POSSIBLE TO PRINT THE BOOK . WHERE DO I GET THE INSTRUCTIONS TO BE ABLE TO PRINT THE BOOK THANK YOU AND LOOKING FORWARD FOR YOUR HELP .

[@ScannerDanner]

You cannot print from the eBook directly. If you just recently bought the eBook, I have no problem applying the cost of the eBook towards a paper book and you can pay the difference. Or if you wanted to have the paper book also, I offer $20 off for eBook owners. Shipping is $5 in the US and $25 overseas. Email me at [e-mail] and add this email address as a contact so my replies do not end up in your spam folder.

[@602mycologist]

Hey scannerdanner, have an 09 charger 3.5 with a starter issue, new starter so I know that’s not the problem, it clicks, I checked the relay and have a voltage drop of around 7 at terminal 86 when I crank it and that’s where I been stuck for a couple of days. I been jumping it from constant to 87 with a switch for now but want to fix it properly. I don’t want to throw parts at it since I’m 17 and don’t have much money. Any advice would be greatly appreciated

[@602mycologist]

I also just replaced the motor and the problem started to occur the following night. This was not a problem before the engine replacement. At first it would start up and after a while it would start up after turning it a few times and now it just doesn’t want to.

[@ScannerDanner]

pretty awesome for a 17 year old! I'd be proud of you if you were my son on how far you've gotten so far. Okay so you are jumping the relay load side contacts to get it to start? (87 and 30) and you have found a voltage drop on the control side (85 and 86)? I think we should move this to my forum as I can definitely help you better there. It is free to join, www.scannerdanner.com/forum.html

[@602mycologist]

Thank you, I have posted my question

[@glasser2819]

this trivial electrical would benefit from a white board explanation... going in current equal going out... PWM voltage control, pwr side Ctl. I feel you made this a bit overcomplicated... like a German car 👍🏻

[@ScannerDanner]

this is a clip from a longer training video, any questions you may have would be answered in the full version, sorry you feel this way

[@georgebonney90]

👍

[@swfloridacarguy1987]

Sounds like a basket case, appreciate all your videos...

[@miriamvivo4279]

Im having similar issue with the subaru evap signal b134 at #13 wire gave up made appt at dealer .finally cleared po448 now have po447 leaning towards bad pcm. Im a retired electrical lineman but just can't grasp your great teching techniques.gave up on g7 computers no one answers phone

[@ScannerDanner]

I seriously doubt it is a bad driver in the PCM. This is a vent control circuit open code right?

[@abubakarisadiqueibrahim481]

What brand of scan tool do you use.

[@ScannerDanner]

the one in this video is Snap-On Verus

[@abubakarisadiqueibrahim481]

@@ScannerDanner Thanks Boss

[@abubakarisadiqueibrahim481]

can see is a very powerful tool, especially the lab scope

[@janakoub1037]

Do you have or know someone like you who can troubleshoot my older Audi here in SF bay area? obd1 scanner does not do much on these cars and everyone hates Audi's.

[@ScannerDanner]

I'm sorry I do not

[@janakoub1037]

@@ScannerDanner Thanks for the quick reply. I guess I go buy the tool and join the program, It's not that difficult.

[@ScannerDanner]

@@janakoub1037 you can also post your questions to my forum, it is free to join and we can definitely help you

[@nickayivor8432]

Good Evening ScannerDanner take care and have a great day ScannerDanner 👍 God bless you ScannerDanner 👍 thanks 👍 bottle of 💧 Good for your body ScannerDanner 🌟 🌟 🌟 🌟 🌟 Tutorial great 👍 👌 👏 Thanks 👍 📷 man got the 👁 for 🎥 🎞 From Nick Ayivor from London England UK 🇬🇧

[@fascistpedant758]

That was short. I figured you'd have more time for videos since the Penguins' season is over.

[@ScannerDanner]

Soon as Caleb graduates high school (16 more school days) you'll see an increase in video production. I'm missing him bad right now...

[@victorlewis8970]

☆☆☆☆☆ perfect.

[@arttorres3612]

How can I get a copy of your book

[@ScannerDanner]

from my website at www.scannerdanner.com Thank you!

[@throttlebottle5906]

watching even though I already knew it was PWM power side ECM controlled ;) jeeps/chrysler products, I hate them lol

[@cru551010]

I would like to get your book.

[@whitetiger8652]

The book is definitely worth the money!

[@ScannerDanner]

It is available through my website at www.scannerdanner.com, thank you!

[@JuanOrtiz-mo8be]

This book is great and its under-priced and underrated . Danner used to give a trial period. I bought it as soon as I learned about it and the book paid for itself on my first diagnostic job.

[@opl500]

High side MOSFET switching is annoying, they avoid it whenever they can

[@salehsalehg8720]

haha haha first tims up hahaha

[@user-zk4nh4te3x]

Начните переводить на русский язык

[@DANNYN224]

Most of the jeep liberty's arent that great

[@ScannerDanner]

The issues on this Jeep apply to output circuits across the board :-), so it is worth watching, I promise.