I've heard you say there are cars with 8volt reference signals. Is this correct? Maybe I'm remembering pull down or up designs. Thank you for the great content.
@@scientist100 yes sir, Chrysler systems from the 80s through the late 90s used a 8-9v reference for the cam, crank and vss inputs circuits, while using a separate 5v ref for the rest of the inputs
Love your videos. Just had to help another tech in my shop after he did an engine swap. Had exactly the same symptoms. He tried swapping the coil, crank and cam sensor from the old engine before I stepped in. After checking crank signal and not finding it, checked 5v reference and did not have one. Computer not so easy to back probe so started unplugging sensors. Found that in the rush of putting the engine back in, he had plugged the cam sensor connector into the coil. Unplugged the coil while watching the 5v reference, boom, 5v now. Easy fix but shows how easy it is to over look something so simple.
I see this was 6 years ago but I am about to go and troubleshoot that exact scenario this weekend and your comment is more useful than you realise, I think you may have already cracked it for me.....I am already on a good path with this one, thanks for the 5volt input dude 😉 👍
Been working on my own stuff for 50 years. Way back before all this complicated stuff. Always looked for obvious first, cracked disconnected hoses and broken wires, burnt wires, chafing wires. Blown fuses, open circuits. All we had were test lights and a multimeter. Now that we have cars on the computers and can bus system it has gone way complicated, but thanks to guys like you us do it yourself types can figure it out again. Back in the day I hung out in the local garage and watched. That is no longer really possible anymore. Thanks to youtube you can hang around thousands of garages.
I'm happy that you enjoy your job very very well and share your knowledge to the technicians who wish they had their co-workers as friendly as you are to help them. I must thank you for 1.) Selling your ebook to me in a printed form 2.) For being a teacher/instructor for all technicians who seek valuable information and testing procedures that you offer us. I greatly appreciate it. Thank you.
I'm addicted to these videos just getting the hang of 5v references unplugging and reconnecting sensors I've ordered a snap on d8 triton was a trade in so got a deal on it now I'm going to start practicing using a scope and values still got a long way to go yet as I'm just starting but your videos are priceless
Thank you! When you're ready, join my classes I offer via my website. I have over 400 hours of training material, from classroom lessons recorded at the technical college i teach at, to exclusive case studies. Hope to see you there! www.scannerdanner.com/join-scannerdanner-premium.html
Congratulations on your 2 years on UA-cam ScannerDanner. i've been following you since the RX300 misfire video and been learning something new ever since. Thanks to you (your E-book, case studies, and video lectures) i've been able to fix vehicles that the "Lead Techs" haven't been able to fix. THANK YOU!...
I have watched 1000's of videos from various authors around the world from UK, Australia etc , spend around 3000 dollar bought lot of dvd (trust me) so far, but ur ebook I bought costed just 30 dollar(not sure how much it is now) and I value that book then those 3000 dollar dvd's... u are the best so far. you know why because u are honest and humble. if the other author have this kind of knowledge like u have they would have sold for million dollar, u are a million dollar guy,
I can't thank you enough for all your wisdom and generosity with it. It sounds crazy but a completed circuit can be applied to just about anything in life.
i am flattered, thank you. But i am nowhere near that mans level. He is so good at what he does. I have so much respect for him. Any class John Thornton is teaching is one that I am signing up for.
After spending a lot of time checking rechecking and re rechecking thinking I missed something, I come across this video that makes sense and is put in simple to understand terms. This procedure makes testing simple and quick. Thank you.
As i research and troubleshoot my Element I am starting to think that mechanics are more electricians than mechanical specialists when dealing with cars. Thanks! Your videos are great and totally make sense to a rookie under the hood.
That is an awesome diagnostic video for someone who is not quite familiar with this situation. But early on in the video I could have told you that the plugs for the map and tps were mismatched. Happens most the time when someone is not careful in their engine swap and hooks them up wrong because they both use the same exact plug.
why should you check for a good 5v Reference? Remember, the 5v-ref. circuit is an output signal from the module used for diagnostic purposes/feedback on wiring integrity. If this is not present, this indicates that the module is not awake. I've seen 7v-ref circuits, 10v-ref circuits etc, but 5volt reference circuits are the most common amongst vehicles, at least from my experience. Awesome video, I thoroughly enjoyed it
Hey Paul if one day you decide to come teach in New York I will definitely be one of your students. Thanks for really teaching how to fix a problem NOT change parts. By watching your videos i decided to buy a Snap on verus pro and now feel like one of your students learning how to use and fix problems with you. Thank you very very much man. May God always keep giving you more and more understanding on how to fix and teach people.
YEp ... great job and very good troubleshooting approach ... I used to do this sort of thing on a brd level at an electronics mfger where we have a test jig for a pcb and it tells us what test fails and then we find that area on the schematic and proceed from there. Golden rule of ANY electronics TSing is power supply power supply power supply ! As you were saying most electronics today are protected from short circuit and over current as well so it makes it pretty easy to track down these sorts of issue. Well done Danner
This is the kind of issue that would have this vehicle jumping from shop to shop with dozens of parts thrown at it..Very few techs would have figured this one out. You're just that damn good man!!
I have a friend with an 05 Dodge Ram 1500 van who is having a similar issue as what you had going on here. It's an intermittent crank but no start, and "no bus" clearly indicated on the cluster, and no data link while this happens. This weekend we will be looking it over. He assumed possibly a bad crank angle sensor, I told him to watch this video since something is possibly grounding out the reference circuit.
I agree with manny mr.danner we realy appreciate you sharing your thought process! Unfortunately in the field most other technicians don't want to teach what they know because they don't want you to start getting more of that work. I rely heavily on my youtube teachers to progress in this field. Thank you very very much
So glad I found your vid ! Changed engine in an altima and same woes. The maf is the only thing I haven't unplugged trying to start w/ no spark. Hope it does it. Thanks.
I have not. I have seen the tool and it is pretty neat. I prefer loaded circuit voltage drop testing myself. I understand there is a need to unplug a circuit to test it at times and this tool could be handy for that.
@@ScannerDanner one confusion....the 5 v reference signal is shared to all sensors. Now, if the 5v signal to MAF is shorted, why the engine can start with the MAF sensor unplugged?? Is not that the ECM will not provide any signal to other sensors too? Please kindly brief clarify. Thanks.
@@tnamen1307 key word "signal", a 5v signal wire on a digital MAF like on a GM, is a pull-down type of circuit. The computer sends 5v to the MAF and the MAF pulls it down to create a digital square wave pattern. This is NOT the 5v reference circuit. Yes, it is tapped into the 5v ref inside of the engine computer, but it is isolated by a current limiting resistor. In short, a 5v signal wire is totally different than a 5v reference wire. Hope that answered your question.
@@ScannerDanner that means, if any sensor or wire sharing a 5 v reference circuit or wire is shorted, then all the respective sensors will not work. Is this my understanding correct??
@@ScannerDanner and, another question relating to ac compressor. My car i20 engine is running very quiet as usual. However, as soon as AC clutch is engaged, I hear a squeak sounds and not metallic sounds or alike. The squeezing like sounds go away immediately as AC is off. Even with engine revs, same sounds. And with AC off, as I revs the engine, still the engine is quiet. How to find that squeaky like sounds and fix it? The AC is blowing cold. It seems the AC compressor is ok.
Yes! Not common but yes. So the process would be to check all powers and grounds, then disconnect ALL sensors that share the 5v ref. Then ohm the 5v ref wire to ground to make sure the harness is good. Then and only then do you look toward the PCM as the fault. At this point we then consider the other variables. Like in this video "2005 Chevy Impala Crank Sensor Trouble Code (P0335)" I almost replaced the PCM in this video for something similar. Variables upon variables my friend :-)
Great instructional video as usual Paul! You are a diagnostic genius to say the least! All your videos are so helpful and chalked full of intuition and accurate persistence! I cant thank you enough! You teaching skills are both top shelf and down to earth. independent thinker inside and out the box. A++++++++++++
60 ur. Old man and I love to work on cars engines .I always avoided eiectrial repair or troubleshoot but now I've so much off of his videos he makes it look. Easy and interesting scanner Danner day shit!!
Hey Paul great test, i agree checking for voltage references from pcm when you dont have communication the first step, test is to verify what the pcm need to supply, which is voltage 5v references ,totally agree,, thanks for sharing
I notice that the odometer reads 141,693 miles even though the engine was swapped out. Could that be a sign of the computer not being able to communicate with the engine? Every time you solve the issue I'm simply blown away. Thank you for the work you do and the effort you put behind these case studies.
Man what an amazing video. I learned a lot about the importance of good reference voltage and how sensors can be interconnected. Thank you. You are awesome.
Very informative, excellent videos, explained well. Nice to not just hear how you do something but why you do it. Also like to see you fast forwarding in areas where it's obvious to do so because of repeated testing of certain components. Your an excellent teacher, look forward to more videos and will definitely take your advice and suggestions of tools and services available that you support that could help me become a better mechanic.
Good Evening Sir ScannerDanner take care and have a great day Sir ScannerDanner Thank you tutorial great 👍 👌 From Nick Ayivor from London England UK 🇬🇧
thank you, this info was a huge help...the sensor did knock off my check ingine light and no start condition... anyway, all is good now..the computer was getting very hot during all my checking but now the fuel relay is malfunctioning and will not start normally... but it will start if I supply voltage to fuel pump... anyway, Ill look at it tomorrow.. thanks again..your awesome.
Another great video. Long time subscriber, and what you prove is that it doesn't matter what car you are working on, you dont need to be experienced with every single car out there, the concepts are fairly identical and therefore so can the troubleshooting. It almost makes me want to purposely create the faults you find, so that I can do the same tests to prove it. My luck though, I'd have the PCM without the "safety" circuitry to handle a short and would blow the PCM, lol.
thank you i have been working on a 2006 subaru wrx no power to the pcm no power to fuel pump no power to injectors and i just went in to work and unpluged the maf and it started right up thank you
Awesum videos you make and yes I spell awesome differently than most people. I have my own reasons for doing it. Some = a few Sum = total. Awesum total amazement. Seems logical to me. Really liked your video, thank you for your time and what a gift to share with us.
Paul danner is the greatest teacher in the u tube there is no point putting tumb down... Mabe those who put their tumb down are those who don't understand or jelouse of his brilliance... Next time if you don't like his teaching you may fuck off without any comments I learned a lot from you Paul thank you ...CLIVE from Malaysia...
you got it my friend. once you know fundamental systems, all cars are the same! Not that you should do it, but every single 5v reference circuit that I have seen shorted to ground, comes back to normal after fixing the short. On some of these you have to turn the key off, then back on for it to come back. Not sure how the PCM is protecting it? Maybe some type of PTC resistor? Anyway, I wouldn't do this one for practice :-)
Is it possible to have a pcm problem with not putting out a 5v? You were getting 1.7volts right at the pcm. If you still had that reading even with all the sensors unplugged would it be a pcm? or would you first check the 5v ref wires from each sensor to pcm before condemning the pcm?
"It isn't just like a regular 5 volt regulator that you buy from radio shack and you short it to ground and you kill it" - The LM7805 has short circuit, overload and thermal protection built in.
I would say only if they are using multiple reference circuits or are somehow able to isolate certain branches of the reference circuit that are drawing too much current flow. I have not seen that yet. You short a 5v ref circuit out and the PCM is "dead" The 5v ref. circuit is the main lifeline of the computer system. It cannot operate without it.
Hi there. My car has no start issues, cranks ok, sparks ok, compression ok, fuel going through, but it won’t start at all, spark plug gets flooded after cranking few times. Then compression gets low. Been to 2 mechanics but no resolution yet. Can you help me out please. I will pay whatever it cost, I wanna learn and solve the issue myself with your help. I have Vcds and can make video and send it to you for analysis & troubleshooting. Look forward to your reply.
ScannerDanner thanks for instant reply, really thankful & appreciated. My car 2006 Golf tsi 1.4 GT (170hp), One thing I forgot to mention, before getting into no starting issue , few days before I mistakenly connected wrong terminals to battery, I mean other way around. Instantly fuse on charger blown with big noise. Now compression, I never had flooding engine before, so I didn’t know about that. I tried to start it for few days, with & without pressing acceleration pedal. This resulted into washed cylinders, engine oil was smelling fuel too, compression at that time was around 30-60 psi in each cylinder. so I flushed engine oil, and then disconnected fuel pump and did the deflood procedure. , compression in each cylinder came back to 130-170 psi in each cylinder. I installed new spark plugs and checked all fuses & relays. I replaced all relays with brand new with the exact part number. But still no success. I have removed the ECU and planning to send it for testing. I also removed high pressure fuel pump and inspected and all seem fine. Do you have any electrical diagram of ecu and it’s plug so that I could check and troubleshoot. Mechanics didn’t say anything about timing, they checked it , VW mechanic took few days and then said that compression might be issue , he was mentioning that one cylinder has low compression. It happens when car is being cranked over and over. Please give me direction to trace the issue. I have VCDS but it’s not very useful than other scanner, I was thinking to buy Delphi or WOW AUTODATA for personal usage, what do you reckon which scanner is best handling most of the issues and affordable too, Really thankful for your kind reply.
this remind me of a time when i was working for a mazda dealership and was first starting out and i had a mazda 626 that was tow in and i try to dianose what was wrong. well i gave up and went and got the lead tech. he came over with a basket of know good electronic parts and told me to try the maf senor first. and what he meant by try the map sensor first was swap it out and see if the 626 will run. well i swap the maf sensor and the car ran. so we informed the customer it need the maf sensor. after the dianose i went back to the lead tech and asked him why the maf fixed the car. and he told me that he dont have a clue. just that his first 626 that he had the problem with took the whole day to figure out with mazda tech support and he just started swapping parts till he found the problem. thank god the car was under warrenty and all the parts where cover. well after seeing this video now i know what was probably happening. we had all the same syptoms as this honda did. by the way there was a computer in that basket that he handed me. be he couldnt get into the computer with the scan tool. so he replaced the computer. Lol im glad i didnt replace the computer. we didnt have a scanner danner back in 2002. thanks for the videos you do.
I once had a 88 aries wagon would just stop unplug map would run replaced numerous times used too keep one in the car a friend at Chrysler told me to move sensor above engine from inside to firewall water accumulation & freeze in winter never happened again
Awesome video actually all your videos are awesome - I'm experiencing similar symptoms and after watching this I'm fairly convinced and hopeful that my issue will be the same. I've already gone through the ignition coil module OPTi spark you name it thank you
+ScannerDanner Thank you so much for your reply... You're truly an amazing technician and a selfless person to share your knowledge and experience, especially at the level of educating others for free. • on my 94 Z28 5.7 L, i took it to an (alleged ASE tech) to work on my vehicle, which I literally never do ever. ( in lieu of my depression & severe anxiety disorder) - "intermittent stalls and no starts" The asshole - "oh, its the opti- $900. Immediately after leaving the shop I go to the car wash & when I try to start the car after washing it, crank no start! "exact same symptoms as when I took it to him. I'm so fucking angry I cant figure out how I'm going to handle this. I did call him right after it wouldn't start of course he didn't answer, it was 20 minutes till close -voicemail: me: " I'm leaving my car up there exact same symptoms"...
Once again dan the Man....super Awsome Knowledge...Almost Master YODA Status...Great stufff Keep the Knowledge a coming...Thanks U a Bunch...U dont Even know how much u just helped me out...Dan the Man!!!
The next time this car is a no start im gonna go out on a limb and say it will be the never start battery, i love walmart but hate there batteries;) Thanks for the amazing videos Paul.
We have 10 of them at the school and they have all been very reliable units. Never sent one in for repairs yet in the 2 years we've had them. These are the first gen. Verus units. They are not wireless. Watch my three part Jeep No start video (10 minutes each) to answer your other question. I have it hyperlinked in this video
Oh yeah ... they both hold a vacuum still ... One more question ... if a MAP is NOT shorted like my junkyard unit but isn't functioning will it still keep the car from starting ? Tested fuel pump pressure and is good at 53 psi for caravan 3.3L ... only other idea I had was suspect fuel pressure regulator but I am not smelling a fuel leak unless the fule is going into the vacuum. I haven't been able to find online WHERE the regulator is for a 2001 Grand Caravan Sport 3.3L. If it has one I suspect it is under the top crap on the intake along the fuel rail ? Or at the fuel pump at the tank ? If pressure is good can it still be regulator ?
Hi I have a Honda crv 2001 with a starting issue..i have checked for the 5v reference but i am showing 4.6v..Would i be right in thinking this is my problem and need to check my grounds.
Brilliant as always , but my question is how can you find or knows that's sensors share Same circuit or voltage ref. if dose NOT shows on the diagrams ?!! And its vary from each make and model ??? I really need to buy your book . Great job
If I have the right the gear I can fix the computer if it has an issue. Schematics are a must ... without them you are flying like Luke Skywalker ... by the seat of the Force. I do have a question as I am working on a 2001 Caravan which no longer runs and suspected the MAP sensor ... sure enough it was pulling my reference down but when tested out of car it was shorted then it wasn't then shorted again. SO put another junkyard unit in and it still won't run ... this time the junkyard unit has a good ref but the signal is nearly the same when it should be around 1 to 1.5v ... it sit at close to reference at 4.62 ish ... so it's the opposite of a short ... and it won't budge under vacuum ... so what ? the diaphragm is stuck ?
Danner bro im having an issue with my 91 civic runs rough seems like when it warms up it runs worst spark is very weak? Ignitor possibly? Timing is dead on. The idle is very rough and the iacv port in the tb is suckin in alot of air creating sort of a vacuum leak im guessing. It stalls at stops once warm. Was the car you diagnosed with the bad ignitor have the same symptoms it was a 92-95 civic i believe. Thx in advance
9 yrs later.. and im amazed how u do ur stuff.. a friend use to call me a jedi when i would fix his pc.. gotta pass it on....jedi👍
Just some fundamental knowledge my friend. This 5v ref. circuit is the same on every car. Thanks!
I've heard you say there are cars with 8volt reference signals. Is this correct? Maybe I'm remembering pull down or up designs. Thank you for the great content.
@@scientist100 yes sir, Chrysler systems from the 80s through the late 90s used a 8-9v reference for the cam, crank and vss inputs circuits, while using a separate 5v ref for the rest of the inputs
Love your videos. Just had to help another tech in my shop after he did an engine swap. Had exactly the same symptoms. He tried swapping the coil, crank and cam sensor from the old engine before I stepped in. After checking crank signal and not finding it, checked 5v reference and did not have one. Computer not so easy to back probe so started unplugging sensors. Found that in the rush of putting the engine back in, he had plugged the cam sensor connector into the coil. Unplugged the coil while watching the 5v reference, boom, 5v now. Easy fix but shows how easy it is to over look something so simple.
I see this was 6 years ago but I am about to go and troubleshoot that exact scenario this weekend and your comment is more useful than you realise, I think you may have already cracked it for me.....I am already on a good path with this one, thanks for the 5volt input dude 😉 👍
@@turtlezed you’re welcome, hope you are successful
Been working on my own stuff for 50 years. Way back before all this complicated stuff. Always looked for obvious first, cracked disconnected hoses and broken wires, burnt wires, chafing wires. Blown fuses, open circuits. All we had were test lights and a multimeter.
Now that we have cars on the computers and can bus system it has gone way complicated, but thanks to guys like you us do it yourself types can figure it out again.
Back in the day I hung out in the local garage and watched. That is no longer really possible anymore. Thanks to youtube you can hang around thousands of garages.
scanner danner best teacher on youtube about car electronic ,briliant teacher.
I'm happy that you enjoy your job very very well and share your knowledge to the technicians who wish they had their co-workers as friendly as you are to help them. I must thank you for 1.) Selling your ebook to me in a printed form 2.) For being a teacher/instructor for all technicians who seek valuable information and testing procedures that you offer us. I greatly appreciate it. Thank you.
I'm addicted to these videos just getting the hang of 5v references unplugging and reconnecting sensors I've ordered a snap on d8 triton was a trade in so got a deal on it now I'm going to start practicing using a scope and values still got a long way to go yet as I'm just starting but your videos are priceless
Thank you! When you're ready, join my classes I offer via my website. I have over 400 hours of training material, from classroom lessons recorded at the technical college i teach at, to exclusive case studies. Hope to see you there!
www.scannerdanner.com/join-scannerdanner-premium.html
Congratulations on your 2 years on UA-cam ScannerDanner. i've been following you since the RX300 misfire video and been learning something new ever since. Thanks to you (your E-book, case studies, and video lectures) i've been able to fix vehicles that the "Lead Techs" haven't been able to fix. THANK YOU!...
I have watched 1000's of videos from various authors around the world from UK, Australia etc , spend around 3000 dollar bought lot of dvd (trust me) so far, but ur ebook I bought costed just 30 dollar(not sure how much it is now) and I value that book then those 3000 dollar dvd's... u are the best so far. you know why because u are honest and humble. if the other author have this kind of knowledge like u have they would have sold for million dollar, u are a million dollar guy,
I can't thank you enough for all your wisdom and generosity with it. It sounds crazy but a completed circuit can be applied to just about anything in life.
Paul i believe God all mighty send you to earth so you can teach us this a gift.thank you sir.
i am flattered, thank you. But i am nowhere near that mans level. He is so good at what he does. I have so much respect for him. Any class John Thornton is teaching is one that I am signing up for.
Lord of the 5V Reference Circuits. Good lesson.
Thank you Jonas! and may God bless your mind as you continue to learn in this great field.
Would never have thought a shorted sensor could cause that. You guys are awesome.
After spending a lot of time checking rechecking and re rechecking thinking I missed something, I come across this video that makes sense and is put in simple to understand terms. This procedure makes testing simple and quick.
Thank you.
what a compliment. thank you very much for all your support!
I've seen a lot of troubleshooting videos on here this is by far the best.Your students are lucky .THANK YOU!
Thank you!
As i research and troubleshoot my Element I am starting to think that mechanics are more electricians than mechanical specialists when dealing with cars. Thanks! Your videos are great and totally make sense to a rookie under the hood.
That is an awesome diagnostic video for someone who is not quite familiar with this situation. But early on in the video I could have told you that the plugs for the map and tps were mismatched. Happens most the time when someone is not careful in their engine swap and hooks them up wrong because they both use the same exact plug.
why should you check for a good 5v Reference? Remember, the 5v-ref. circuit is an output signal from the module used for diagnostic purposes/feedback on wiring integrity. If this is not present, this indicates that the module is not awake. I've seen 7v-ref circuits, 10v-ref circuits etc, but 5volt reference circuits are the most common amongst vehicles, at least from my experience.
Awesome video, I thoroughly enjoyed it
Hey Paul if one day you decide to come teach in New York I will definitely be one of your students. Thanks for really teaching how to fix a problem NOT change parts. By watching your videos i decided to buy a Snap on verus pro and now feel like one of your students learning how to use and fix problems with you. Thank you very very much man. May God always keep giving you more and more understanding on how to fix and teach people.
Excellent video. I had a shorted TCM pulling down all com on a Mercedes I bought. You're doing a terrific job enlightening others. Thanks!
YEp ... great job and very good troubleshooting approach ... I used to do this sort of thing on a brd level at an electronics mfger where we have a test jig for a pcb and it tells us what test fails and then we find that area on the schematic and proceed from there. Golden rule of ANY electronics TSing is power supply power supply power supply ! As you were saying most electronics today are protected from short circuit and over current as well so it makes it pretty easy to track down these sorts of issue. Well done Danner
This is the kind of issue that would have this vehicle jumping from shop to shop with dozens of parts thrown at it..Very few techs would have figured this one out. You're just that damn good man!!
I have a friend with an 05 Dodge Ram 1500 van who is having a similar issue as what you had going on here. It's an intermittent crank but no start, and "no bus" clearly indicated on the cluster, and no data link while this happens. This weekend we will be looking it over. He assumed possibly a bad crank angle sensor, I told him to watch this video since something is possibly grounding out the reference circuit.
Probabky bad ecm
been watching your videos,but this is the first time I write,thank you for all your videos, and this one is one of the best.
I agree with manny mr.danner we realy appreciate you sharing your thought process! Unfortunately in the field most other technicians don't want to teach what they know because they don't want you to start getting more of that work. I rely heavily on my youtube teachers to progress in this field. Thank you very very much
Well done.So amazing to look at you and going stepby step and that referenced 5 volts is awesome.
Thank you!
for sure it seems like it would be a great addition to the diagnostic tool box for that type of testing.
Thank you for being clear and concise in your videos. You may have just helped me figure out where to look next.
I saw this one when it dropped and again now. Still an awesome watch.
Amazing how sensitive the computer is missing just a few volts which can cause big problems. Great vid once again, thanks!
My best lecturer. Always wish i knew you earlier. Am learning alot. Thanks.
Love this comment. Thank you
So glad I found your vid ! Changed engine in an altima and same woes. The maf is the only thing I haven't unplugged trying to start w/ no spark. Hope it does it. Thanks.
I have not. I have seen the tool and it is pretty neat. I prefer loaded circuit voltage drop testing myself. I understand there is a need to unplug a circuit to test it at times and this tool could be handy for that.
what an excellent video, extremely good information for going after a no start .
Thanks John
@@ScannerDanner one confusion....the 5 v reference signal is shared to all sensors.
Now, if the 5v signal to MAF is shorted, why the engine can start with the MAF sensor unplugged?? Is not that the ECM will not provide any signal to other sensors too? Please kindly brief clarify. Thanks.
@@tnamen1307 key word "signal", a 5v signal wire on a digital MAF like on a GM, is a pull-down type of circuit. The computer sends 5v to the MAF and the MAF pulls it down to create a digital square wave pattern. This is NOT the 5v reference circuit. Yes, it is tapped into the 5v ref inside of the engine computer, but it is isolated by a current limiting resistor. In short, a 5v signal wire is totally different than a 5v reference wire. Hope that answered your question.
@@ScannerDanner that means, if any sensor or wire sharing a 5 v reference circuit or wire is shorted, then all the respective sensors will not work. Is this my understanding correct??
@@ScannerDanner and, another question relating to ac compressor.
My car i20 engine is running very quiet as usual. However, as soon as AC clutch is engaged, I hear a squeak sounds and not metallic sounds or alike. The squeezing like sounds go away immediately as AC is off. Even with engine revs, same sounds. And with AC off, as I revs the engine, still the engine is quiet. How to find that squeaky like sounds and fix it?
The AC is blowing cold. It seems the AC compressor is ok.
the best teacher in the world.you are brilliant sir
Excellent, definitely the best learning resource on the web.
excellent video paul i think between just these last 2 videos/ they cover all steps approaching any no-start condition.
Great case study Paul. We sure have to pay attention on those shared 5V references even if they coming from two separate pins in computer.
Yes! Not common but yes. So the process would be to check all powers and grounds, then disconnect ALL sensors that share the 5v ref. Then ohm the 5v ref wire to ground to make sure the harness is good. Then and only then do you look toward the PCM as the fault.
At this point we then consider the other variables. Like in this video "2005 Chevy Impala Crank Sensor Trouble Code (P0335)"
I almost replaced the PCM in this video for something similar.
Variables upon variables my friend :-)
this is another great video always some thing to learn, good lesson Paul thank you . the best teacher I ever seen. your book is amazing
Omg this is by far my favorite video this is the stuff that will drive you crazy and you systematically took it on step by step
Great instructional video as usual Paul! You are a diagnostic genius to say the least! All your videos are so helpful and chalked full of intuition and accurate persistence! I cant thank you enough! You teaching skills are both top shelf and down to earth. independent thinker inside and out the box. A++++++++++++
60 ur. Old man and I love to work on cars engines .I always avoided eiectrial repair or troubleshoot but now I've so much off of his videos he makes it look. Easy and interesting scanner Danner day shit!!
Hey Paul great test, i agree checking for voltage references from pcm when you dont have communication the first step, test is to verify what the pcm need to supply, which is voltage 5v references ,totally agree,, thanks for sharing
I notice that the odometer reads 141,693 miles even though the engine was swapped out. Could that be a sign of the computer not being able to communicate with the engine?
Every time you solve the issue I'm simply blown away. Thank you for the work you do and the effort you put behind these case studies.
Man what an amazing video. I learned a lot about the importance of good reference voltage and how sensors can be interconnected. Thank you. You are awesome.
Very informative, excellent videos, explained well. Nice to not just hear how you do something but why you do it. Also like to see you fast forwarding in areas where it's obvious to do so because of repeated testing of certain components. Your an excellent teacher, look forward to more videos and will definitely take your
advice and suggestions of tools and services available that you support that could help me become a better mechanic.
Thank Paul for explaining the 5 v reg great job man thank you sir.
Good Evening Sir ScannerDanner take care and have a great day Sir ScannerDanner
Thank you tutorial great 👍 👌
From Nick Ayivor from London England UK 🇬🇧
omg ..so much to learn from you...and this video have 10 years
Still just as relevant today my friend. Thank you!
you are very welcome, and thank you for the comment
thank you, this info was a huge help...the sensor did knock off my check ingine light and no start condition... anyway, all is good now..the computer was getting very hot during all my checking but now the fuel relay is malfunctioning and will not start normally... but it will start if I supply voltage to fuel pump... anyway, Ill look at it tomorrow.. thanks again..your awesome.
Another great video. Long time subscriber, and what you prove is that it doesn't matter what car you are working on, you dont need to be experienced with every single car out there, the concepts are fairly identical and therefore so can the troubleshooting. It almost makes me want to purposely create the faults you find, so that I can do the same tests to prove it. My luck though, I'd have the PCM without the "safety" circuitry to handle a short and would blow the PCM, lol.
Hey Paul, Great video you have convinced me to buy your book, all the best from the UK.
thank you i have been working on a 2006 subaru wrx no power to the pcm no power to fuel pump no power to injectors and i just went in to work and unpluged the maf and it started right up thank you
Thanks for the great job of making us great technicians
Awesum videos you make and yes I spell awesome differently than most people. I have my own reasons for doing it.
Some = a few
Sum = total. Awesum total amazement. Seems logical to me.
Really liked your video, thank you for your time and what a gift to share with us.
Thank you very much for that write up (video). It was very informative and very helpful in regards to "no start" issues.
A superb logical approach. Another fault finding gem. Thanks for posting this.
my english its not to good but im learning all the inf you shareand at the same time im learning english thank you for techihng us God bless you
You are welcome!
Quick question. Why do most sensors use a 5v ref voltage? Why not 1v or 2v in general? What's so appealing for auto manufacturers to stick with 5v?
if there s check engine light, with the key on...could we assume that it s likely the shorted sensor/5v ref...rather than computer pwr n gnd issue?
Paul danner is the greatest teacher in the u tube there is no point putting tumb down... Mabe those who put their tumb down are those who don't understand or jelouse of his brilliance... Next time if you don't like his teaching you may fuck off without any comments I learned a lot from you Paul thank you ...CLIVE from Malaysia...
lol thanks man
you got it my friend. once you know fundamental systems, all cars are the same!
Not that you should do it, but every single 5v reference circuit that I have seen shorted to ground, comes back to normal after fixing the short. On some of these you have to turn the key off, then back on for it to come back. Not sure how the PCM is protecting it? Maybe some type of PTC resistor? Anyway, I wouldn't do this one for practice :-)
ScannerDanner so that means need a new map sensor?
very good presentation on ref. voltage,and seeing if computer is alive.
I I
check your fuel psi and if it has a MAF sensor make sure the air intake tube has no cracks in it and that the MAF sensor checks out good.
Hi Paul, fix the 5 V. fix the no communication?
Is it possible to have a pcm problem with not putting out a 5v? You were getting 1.7volts right at the pcm. If you still had that reading even with all the sensors unplugged would it be a pcm? or would you first check the 5v ref wires from each sensor to pcm before condemning the pcm?
"It isn't just like a regular 5 volt regulator that you buy from radio shack and you short it to ground and you kill it" - The LM7805 has short circuit, overload and thermal protection built in.
I would say only if they are using multiple reference circuits or are somehow able to isolate certain branches of the reference circuit that are drawing too much current flow. I have not seen that yet. You short a 5v ref circuit out and the PCM is "dead"
The 5v ref. circuit is the main lifeline of the computer system. It cannot operate without it.
Hi there. My car has no start issues, cranks ok, sparks ok, compression ok, fuel going through, but it won’t start at all, spark plug gets flooded after cranking few times. Then compression gets low. Been to 2 mechanics but no resolution yet. Can you help me out please. I will pay whatever it cost, I wanna learn and solve the issue myself with your help. I have Vcds and can make video and send it to you for analysis & troubleshooting. Look forward to your reply.
What are your compression numbers?
Have you removed the upstream O2 to see if it starts (quick and dirty plugged cat test)
ScannerDanner thanks for instant reply, really thankful & appreciated. My car 2006 Golf tsi 1.4 GT (170hp), One thing I forgot to mention, before getting into no starting issue , few days before I mistakenly connected wrong terminals to battery, I mean other way around. Instantly fuse on charger blown with big noise.
Now compression, I never had flooding engine before, so I didn’t know about that. I tried to start it for few days, with & without pressing acceleration pedal. This resulted into washed cylinders, engine oil was smelling fuel too, compression at that time was around 30-60 psi in each cylinder. so I flushed engine oil, and then disconnected fuel pump and did the deflood procedure. , compression in each cylinder came back to 130-170 psi in each cylinder. I installed new spark plugs and checked all fuses & relays. I replaced all relays with brand new with the exact part number. But still no success. I have removed the ECU and planning to send it for testing. I also removed high pressure fuel pump and inspected and all seem fine. Do you have any electrical diagram of ecu and it’s plug so that I could check and troubleshoot. Mechanics didn’t say anything about timing, they checked it , VW mechanic took few days and then said that compression might be issue , he was mentioning that one cylinder has low compression. It happens when car is being cranked over and over. Please give me direction to trace the issue. I have VCDS but it’s not very useful than other scanner, I was thinking to buy Delphi or WOW AUTODATA for personal usage, what do you reckon which scanner is best handling most of the issues and affordable too, Really thankful for your kind reply.
This changes everything. You need to watch these two videos
ua-cam.com/video/hJQ6qnhTgdg/v-deo.html
ua-cam.com/video/ecz93B5SRsQ/v-deo.html
I love the credits at the end...starring: a shorted map sensor 🙂
I wish we had Mitchell on demand wiring diagrams in the uk! Great video by a great teacher!
Bravo, that is troubleshooting on another level. Great lesson.
Excellent. Paul. Love the direction
another really good video. spot on with the method paul. learn along with danner is better than factory training.
Wow this is so sweet you are so good in what you do i keep looking at this video over an over very nice.
Great case study as usual. Thank you very much. I love learning and being stepped through your thought process.
this remind me of a time when i was working for a mazda dealership and was first starting out and i had a mazda 626 that was tow in and i try to dianose what was wrong. well i gave up and went and got the lead tech. he came over with a basket of know good electronic parts and told me to try the maf senor first. and what he meant by try the map sensor first was swap it out and see if the 626 will run. well i swap the maf sensor and the car ran. so we informed the customer it need the maf sensor. after the dianose i went back to the lead tech and asked him why the maf fixed the car. and he told me that he dont have a clue. just that his first 626 that he had the problem with took the whole day to figure out with mazda tech support and he just started swapping parts till he found the problem. thank god the car was under warrenty and all the parts where cover. well after seeing this video now i know what was probably happening. we had all the same syptoms as this honda did. by the way there was a computer in that basket that he handed me. be he couldnt get into the computer with the scan tool. so he replaced the computer. Lol im glad i didnt replace the computer. we didnt have a scanner danner back in 2002. thanks for the videos you do.
I once had a 88 aries wagon would just stop unplug map would run replaced numerous times used too keep one in the car a friend at Chrysler told me to move sensor above engine from inside to firewall water accumulation & freeze in winter never happened again
Randy Johnson where can I buy a magic basket of goodies like your buddies
Awesome video actually all your videos are awesome - I'm experiencing similar symptoms and after watching this I'm fairly convinced and hopeful that my issue will be the same. I've already gone through the ignition coil module OPTi spark you name it thank you
+Kevin cool. Let me know if you fix it
+ScannerDanner
Thank you so much for your reply...
You're truly an amazing technician and a selfless person to share your knowledge and experience, especially at the level of educating others for free.
• on my 94 Z28 5.7 L, i took it to an (alleged ASE tech) to work on my vehicle, which I literally never do ever. ( in lieu of my depression & severe anxiety disorder) - "intermittent stalls and no starts"
The asshole - "oh, its the opti- $900. Immediately after leaving the shop I go to the car wash & when I try to start the car after washing it, crank no start! "exact same symptoms as when I took it to him. I'm so fucking angry I cant figure out how I'm going to handle this. I did call him right after it wouldn't start of course he didn't answer, it was 20 minutes till close -voicemail: me: " I'm leaving my car up there exact same symptoms"...
"Engine swap" ran before..what changed?
Look for wires not plugged in or grounds loose.
Once again dan the Man....super Awsome Knowledge...Almost Master YODA Status...Great stufff Keep the Knowledge a coming...Thanks U a Bunch...U dont Even know how much u just helped me out...Dan the Man!!!
"There is no try. There is only do."
shared circuitry my friend. ALL automotive systems do it this way.
The next time this car is a no start im gonna go out on a limb and say it will be the never start battery, i love walmart but hate there batteries;) Thanks for the amazing videos Paul.
We have 10 of them at the school and they have all been very reliable units. Never sent one in for repairs yet in the 2 years we've had them. These are the first gen. Verus units. They are not wireless.
Watch my three part Jeep No start video (10 minutes each) to answer your other question. I have it hyperlinked in this video
Gracias, gracias, gracias!!! Straight to the point, and clear as daylight explaning. ✌😎 New sub. Stay 💪. Thank you very much.
Thank you so much! And welcome to my channel
Oh yeah ... they both hold a vacuum still ...
One more question ... if a MAP is NOT shorted like my junkyard unit but isn't functioning will it still keep the car from starting ? Tested fuel pump pressure and is good at 53 psi for caravan 3.3L ... only other idea I had was suspect fuel pressure regulator but I am not smelling a fuel leak unless the fule is going into the vacuum. I haven't been able to find online WHERE the regulator is for a 2001 Grand Caravan Sport 3.3L. If it has one I suspect it is under the top crap on the intake along the fuel rail ? Or at the fuel pump at the tank ? If pressure is good can it still be regulator ?
Hi I have a Honda crv 2001 with a starting issue..i have checked for the 5v reference but i am showing 4.6v..Would i be right in thinking this is my problem and need to check my grounds.
Brilliant as always , but my question is how can you find or knows that's sensors share Same circuit or voltage ref. if dose NOT shows on the diagrams ?!! And its vary from each make and model ??? I really need to buy your book . Great job
Luv theses type of case studies, great for dirrection base.. GURU!!!
If I have the right the gear I can fix the computer if it has an issue. Schematics are a must ... without them you are flying like Luke Skywalker ... by the seat of the Force. I do have a question as I am working on a 2001 Caravan which no longer runs and suspected the MAP sensor ... sure enough it was pulling my reference down but when tested out of car it was shorted then it wasn't then shorted again. SO put another junkyard unit in and it still won't run ... this time the junkyard unit has a good ref but the signal is nearly the same when it should be around 1 to 1.5v ... it sit at close to reference at 4.62 ish ... so it's the opposite of a short ... and it won't budge under vacuum ... so what ? the diaphragm is stuck ?
very good testing procedure diagnostic flow chart.thankyou for sharing we always learn somethign from you....
Another simple video that is understood
Danner bro im having an issue with my 91 civic runs rough seems like when it warms up it runs worst spark is very weak? Ignitor possibly? Timing is dead on. The idle is very rough and the iacv port in the tb is suckin in alot of air creating sort of a vacuum leak im guessing. It stalls at stops once warm. Was the car you diagnosed with the bad ignitor have the same symptoms it was a 92-95 civic i believe. Thx in advance
This is one of my favorite videos really enjoyed this one!!
that is correct my friend
I'm not but thank you Hector! You made my evening.