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
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)
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:

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!

[MitchellHenderson]

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..

[amadoterte]

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.

[wyattoneable]

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

[billyyoder]

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

[josealers]

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

[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
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)
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

[CameronDC-Grimes]

Hey Paul Danner, nice videos as always. I've learned more from you in 1 year that i ever did from 10 years working on cars under mechanics and wirking for an excavation equipment company under the lead mechanic.
I now have the OTC 3633 mini coiled circuit tester (incandescent bulb) because i seen you using it in some premium videos.

[andrewk]

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

[AzFL]

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

[theadventuresofjavier]

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. 🙏

[jahrain]

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

[parochial]

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

[mohammedcherifi]

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

[vincescalise]

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.

[koltencanfield]

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

[billyyoder]

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

[alexmessina]

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.

[jeremieparker]

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

[tigerksewsankar]

Love all your videos paul thank you ..