Nissan No Start, No Comm (Shorted 5V Reference?)
Вставка
- Опубліковано 24 сер 2024
- Here's a quick diag on a 2004 Nissan XTerra V6 that came to the shop with a misfire, but after the repairs it refuses to start!!
No communication with the scanner.
The shop owner wants a definite answer, because the Parts Cannon is OUT OF AMMO!
Before calling a bad Engine Computer, how do you quickly check the 5V reference for a short to ground?
Enjoy!
Ivan
![АЛАУДИНОВ у Скабеевой: эти их ВСУ нас НЕ ДОГОНЯТ 😁 [Пародия]](http://i.ytimg.com/vi/an0anqU4WGQ/mqdefault.jpg)
Man...idk of any other mechanic that would be able to figure out the type of calls you get. This is some advanced grandmaster diagnostics right here
Always disconnect the battery before doing any engine work. If one of the grounds is removed from the engine block it can blow the ecu.
On a later model BMW if you remove the ground on the valve cover and turn the key on it will blow the dme (ecu).
They put out a technical bulletin on this and will not pay (w) on a blown dme (ecu). Not saying this was the case here.
Just FYI.
Wow it's amazing how you are able to definitively pinpoint a fault like this. I watch a lot of UA-cam mechanics/Auto Diagnostics and you are by far the most forensic in your approach and probably the smartest. Have to say Scotty Kilmer is more entertaining and he is broadly knowledgeable, but that's what makes UA-cam great, there is room for everybody!
Scotty will never own a fly swatter.
Quick demonstration of the issue. Tools and knowing how to use them will save time and make the job easier.
Thanks Ivan!
Bah. Sounds like in the future you need to pester people to not throw away the part. Maybe offer them a pack of beers for it or something so they don't forget. We need our bonus footage! :)
Ivan, I just did this exact same job on a 2004 Xterra last week. Customer was driving the car, parked it in their driveway and then crank no start. I checked for spark and fuel pressure and there was nothing. No communication with ecm. I threw a used ecm in it and it fired right up! This Xterra has 41k on it and is mint otherwise, all stock. No evidence of water intrusion or electrical smells either.
Nissan come in my shop with bad ecm bad coils …… I always find broken rotted ground straps . Especially on the Nissan Murano . .
Hi Ivan -- nice strategizing not just a method, but a fast method. That said, my EE hat says that if you're going to pull up a 5V rail, you really should pull it up to only 5V (still through a current-limiting device, such as 5 or 6V incandescent lamp) for maximum collateral damage avoidance. Like in this case, your 5V bus rose to ~12V when the ECU was disconnected... because, as you noted, the loads on that line only draw a few milliamps, so are much higher resistance than your "300mA" bulb. Hopefully those 5V automotive components are built to withstand the overvoltage!
Man I love the quick test. But Im wth you Graham. I got sweat beads on my brow just watching Ivan plug in 5v. I get that it's a protected circuit, but is every make and model equally protected or is it Russion Roulette?? I suppose you could use a 5v regulated input, but it's then tricky cause you need to rig it up or make it ... it's not quick any more. Does anyone know for a fact that all these circuit can withstand a 12v input?????
@@alexmessina3383 5V supply is not too difficult. You can use a cigarette lighter USB plug, or a USB battery pack, for example.
He uses a 3w bulb. That means the 5v line only gets a max of 148mA. This methode is also how you connect a led to a powersource. Voltage doesn't matter. It's the current that needs to be dissipated.
@@k1n2g4 yep also I suppose u can use a 5v batt charger or Graham’s suggestions. But 148mA is heaps on a 5v circuit. The usual pwr source is via the internal PCM 5v regulator and depending on internal design it may be routed via a series of resistors and then thru low current transistors before exiting to sensors ... pushing Vs and mAs the other way into PCM, well, maybe no issues when it hits internal component in opposite direction. These circuits ‘should’ be designed to withstand a short to 12v power. But find some service info for a particular model and PCM design that confirms that? I doubt it’s there. What abt ohming to ground instead of bulb?? Depends on current output from DVOM I suppose. But it was a good dish in this case and it worked👍
Yeah I was waiting for snap crackle pop…
Interesting....🤔
Eric! How's it going! Hope things are well in Avoca 🙂
Eric was just saying how much he loved Fords the other day
Fords are Eric Os favorite vehicles to work on 🤣
How are you Erich ?
Eric was saying how much he liked mobile diagnostic jobs ......... NOT !
Seeing that banged-up Ford work truck lurking behind you like a Great White Shark made me nervous. Obviously, that owner is not a very careful driver. Stay safe Ivan!
Yeah I waiting for it to catch the end of the door and rip it off!
Simple yet brilliant! This one is so simple I can’t believe I’ve never thought of this before. I will definitely be applying this to my own testing procedure. Thanks for sharing
It's going to be a tense moment plugging in the new ECM.
Wow just love the way you think things thru!!! Great job Ivan! That's why the shop called you!!!
This shop is pretty good at diagnostics so they only call me as a last resort haha
Ivan what the hell?No bonus video. Quick video, I felt robbed.😁5volt ref is the 🗝️ thou.good job bro.😂
Yeah come on Ivan. Bonus footage man. Maybe bake a cake or something at least
Good move Ivan...it keeps everyone at attention !
@@Garth2011 😆.
What a saga. Giving that one back had to feel more like relief than a win.
Good Find Ivan! As a Electronic Technician, I don't believe it was coincidental failure. Probable causes, they failed to disconnect the Battery before starting their maintenance, or plugged a connector while power ia applied. Anyways , the customer now pays for the replacement unit.
Ivan is fantastic. This is one of the few channels where I watch *every* video.
Everytime if that ECM isnt putting out that 5V you already know!!!!! Great video brother!!!!!
Great job once again, I love to follow your logic as you work.
Bad shop we wanted extra footage they are always so satisfying to see
Quick and dirty diagnosis, it sucks that no bonus footage ama would love to see the old ecm and see what failed, that would be epic!!
Oh no! No Ivan post mortem. I feel cheated!🤣
The smell of the magic blue smoke never lies.
Great lesson, instead of the way Bernie using, generating a signal to the system, Ivan teaches a more efficient and simple way to check the short.
ECM might have originally been the reason for the misfires, and the computer was already on the fritz. If the shop did something as simple as turn the key on with a battery charger hooked up and provided 1 extra volt to the power feeds of the computer, it might have just been the straw that broke the camel's back.
camel's back lol, you must live around camels to reference a camel for something like this unless I'm missing something obvious lol
@@scientist100 it is a saying"the straw that broke the camels back"
Yes, very possible and try explaining that to a customer after the initial repairs and expense. whoa
I thought it went thru PCM to confirm short
It sucks but it happens, I've had it happen to my own vehicle, needed a starter a few days after CV shafts were replaced, anytime you work on older vehicles you disrupt the general state of things
Yes Sir, once your car knows you had some
money stuff is going to fail!!
🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
I need to tell you my personal story. I replaced the iacc valve and i remove the intake manifold and ground on it and turn on the ignition and kaboommm no start it results that the ground on the manifold is the main pcm ground and ignition on will turn on the pcm. Lesson learn always disconnec the battery.
Nice find Ivan!! I wonder if it's had
water from the evap core dripping
on it this summer due to a plugged
evap drain?? Back in the day when
I was a GM tech we would see stuff
like that thru the summer months
from customer running AC and
Spiders would make their home
in the drain tube blocking it!!!
Those Ford trucks had a good idea too, they installed the PCM right under the degas reservoir !
I was a cat tech back in the day. I chased the spider nest on a grand prix forever it seemed. Wish someone had posted this back then as i spent countless hours before I found it.
Wow way to show and explain how simple u did the test when u know the way system works makes so much sense I would’ve unplugged every sensor Thank you for Sharing .
A little trivia: Did you know that one of the stars in the constellation Big Dipper is named Phad?
If you join the stars you can seen Ivan's face:-)
Maybe I missed it but I didn't hear you mention that the 5V supply in the ECM might (varies from vehicle to vehicle) feed multiple '5V reference' output pins, so definitely want to verify there aren't additional 5V ref lines that could be shorted.
I'd be careful putting vbat on the 5v reference. Usually it is connected right to the internal 5v rail inside the ECU with not much protection (Only a zener diode normally).
Ivan I look forward to every adventure. 12 volts on a 5 volt line. Hmmm I wonder about this. Another great job.
It's save. It doesn't put more than 145mA on the network. This is also how you hookup led lights to a powersupply. The 3w bulp acts as a 48ohm resistor.
👋Sir very nice diagnostic, I think the high voltage from the bad coil arc moving to the low voltage, truth a bad ground..blessings
Good systematic approach to diag nice Ivan
I think u should explain why the test light goes out when the bulk head connector is unplugged and the scope reads 12 volts.
That was a good end of tests confirmation. If the light had stayed lit then the short would have been external of the computer and with it reading 12 volts and unplugged the ckt wasn’t being pulled to ground. Interesting that the initial voltage was pulled up from 700 mv to 3 volts, so it must have been a partial short or even a blown diode inside or cap. Interesting though.
Thanks for sharing this nice troubleshooting tip.
Hey Ivan I have a friend who has one of those and he needed a jump start, but one of the battery terminals was loose and extremely corroded, so he ended getting a new ecm and alternator and a few other devises that got fried from over voltage because of no battery reference .The jump came from an old unregulated battery charger, the output was 18 volts.
Geeesh overcharged up to 24v lol
Putting 12v+ on the 5v ECM output would make me nervous.
5v ref is an extremely rugged circuit.
Same LOL
Who the hell gave a thumbs down already. Scotty is that you
Gotta be a mistake, no one is that stupid . . . one would hope.
Sounds like a bad ECM. What the shop did was right, after all 😁 Scotty Kilmer diagnosed nearly the same symptoms on an Acura RDX a long time ago. That was due to a bad multimedia system computer circuit. Always costly to fix, these symptoms.
Simple . The shop killed the battery and some bone head didn’t want to wait for the battery to charge and turned the charger to that stupid 50amp engine start and smoked the computer. I’ve seen this happen a bunch of times . I heard of a person who smoked the ecm, Tcm, airbag module and 3 amplifiers a touchscreen head unit and a dsp . Let’s just say the customer lost his shi! When he found out. His wife had to bring him Valium to calm him down . Worst part is the mechanic tried to hide it 😂. Thank god for cameras . You could actually see him hook the charger and switch it to engine start and the smoke came out from every where . . He pushed the car to the finished/pick up spot . How do you kill the battery doing a oil change?? He left the key on and didn’t feel like putting the lift down to turn it off . 😳🤯. In my opinion that engine start crap shouldn’t be on the heavy duty shop battery chargers . Use a jump box like every one else does . Less issues that way . Thanks for the video Ivan !!!
Wow that would make me very upset,😢
@@PineHollowAutoDiagnostics what is an engine start?! How exactly does that fry things?
@@awaara24 same question here. I have one of those chargers.
An expert is someone you call in to take 50% of the blame when something goes wrong.
Do you keep a Printer on your vehicle to print out all those wiring diagrams?
just learned about the bit flip the z particles do to binary code once in awhile that would throw you off in a diag eh
Hi Ivan just wondered if you could temporarily put a 5 volt supply to the wire see what happens, like from some batteries or modified PC power supply...they have i think a 5 volt output...Fred.
I bet that ECM has a nice black spot on the board, where it cooked a little.
Another great video.
Great tip. Very cool. Thank you ivan
Top notch Ivan! I wonder what was the cause of it! Thanks for sharing!
But....
Did you "do the grounds"!? LoL 😂😆
That’s funny. I remember that coming up in a SMA video.
iVAN is a GENIUS !!! !!!
I'm just about convinced that a law needs to be in place that automotive modules must be built to last a good 15 years+ or the manufacturer must replace them at no cost. The public is getting the shaft big time on these overly designed and highly engineered vehicles. In the end, all of these electronics are in some way related to EPA pollution controls so the manufactures should be forced to fix them for free as they fail or be required to build them with more robust materials to that in the years following discontinuation of parts production, a car owner is not high and dry 15 to 20 some years later over one small plug in part !!
You first found that multiple modules did not communicate, but why did you check the 5v output in the first place?
That's why you always check/read the code's first and look at live data and make sure that you have spark then go for there
Cool diag. Thanks Ivan !
Well thought out Diag... Maybe a post Renault/Nissan merge special
Like #799
Thanks for the video!
Life is a learning curve!
Hindsight is 20-15!
That is bad timing and a tough one to relate to a customer, for sure. Most logical thinking would say, "what about the other repairs that we did, were they necessary now that the PCM failed"? I'm glad I don't have to explain that and the extra costs to the customer.
Someone hooked up a battery or booster cable in revers , that would certainly do it.
Had an o5 f150 today blowing black smoke out the tailpipe hardly running. Turned out power steering pressure sensor pulled the 5 volt reference
Great job Ivan!!!
NO BONUS FOOTAGE!?
Is it always safe to put 12v on the 5v output?
yeah i was cringing when he done that. some circuits are fine others not. without knowing id have fed it 5 volts on a 5 volt circuit. its not only the computer to worry about its sensors too.
Yeah it's fine through a low amp test light. 5V circuits are high impedance, and are designed to be robust enough to be shorted to power or ground and set a code instead of burning up 🙂
remember current/amperage is a killer ;D
Hey boss 😎. So I have a question. What if the sensors have grounds from the ecm? So the 5v wire out you've given 12v but a shorted sensor may not go to ground if you removed the bulk connector from ecm. No ground available ... just something to chat about of course
@@NewLevelAuto brilliant comment as usual Keith! I'll have a 2000 XTerra to play with next week, will have to explore this and make a follow up video 👍😁
Mechanic initially reversed battery cables and tried to start it. That's my guess😁
That was my first guess too, but shop owner assured me that he was the only one who connected the battery and paid attention 😉
@@PineHollowAutoDiagnostics I would say the same as the shop owner, I guess...
well reversed cables, i would think would blow the large fuse first, wouldnt even make it to the computer... but stranger shit has happened
@@ttstang43 if your lucky it blows the main fuse but it does frequently fry the ecm. Computer's no likey reverse voltage😜
So using a test light connected to 12 volts and touching on a 5v reference wire to check for a short won't hurt the circuit? I like that test. Thanks
Just wondering if you unplugged the pcm wouldn't that also eliminate the ground. If a sensor was shorted internally or a harnessed shorted together (5v ref and low ref) wouldn't it read open because you removed the ground by unplugging the pcm. I diagnosed a similar issue yesterday and tested it the exact sameway with same results. After getting home and thinking about it im wondering if I messed something 🤔
Would have been nice to do a dive into that box!
He always does a great job!…lol
I like that trick! Sure beats trying to unplug 100 sensors with ZERO accessibility. Someone let the smoke out of the magic box! Ahh crap!!
My brother bought this exact year & model way back. Been a while since I've seen one - they've all rotted away to the scrap yard! He had it all set up for off-roading. That poor, anemic V6 had all it could do to get out of it's own way, lol. Terrible mileage, even when stock and brand new. A good crusher candidate! :D I threw a timing belt in it before he sold it. Actually wasn't that bad of a job, shockingly enough. :)
Gross auto get worst mpg lol. I drove automatic long time ago. It feel less power and mpg is like 10-15.
Older manual with rwd has more power and better longer mpg than new with auto.
6:00 nice Ford Bumper.. looks like it did some of its job lol
Excellent tip
Check five volt reference ! After pos and grds fuses etc. Did they remove battery negative, bet they didn’t. I messed up a pcm on my own car once basically doing that same job. Valve gaskets etc.
Great bother
Nice job and video like always
Sounds like the ECM was already on it`s way out with the crappy way it was running. Then it gave up the ghost when it finally shorted out.
Mismatch timing and incorrect firing will cause ECM shorted by coils's electrical loads.
Hello sir, good work .where do I get wiring diagrams for nissans
So the big question in my mind is did they tell the owner about all this and that he now has a junkyard pcm in his car? Not saying I'd be pissed but I'd want to know. Nice troubleshooting Ivan.
You da man Ivan!
Thats a fast way to diagnose ECM. When the bulk connector gets unplugged why did it go to 12 volts? I thought that was the 5 volt reference circuit.
The power was from the cigarette lighter.
@@_RiseAgainst Oh yeah. Because the ECM wasn't putting out the 5 volts.
Dr's. bury their mistakes, shops throw theirs in the trash.
Nice work!
My guess, bad distributor. Happened to me after replacing the. Verified it by the book and figured it out in seconds.
Did they not disconnect the battery when they were doing all that work? I can’t see them not pulling the battery for extra space , room and typical logic. You start doing anything under the hood (besides checking oil or fluids lol),the first thing you should do and are told to do so often it’s gotta be one of the first things most people do when they start a under the hood repair job,tuneup, etc.
So what really happened?
bet the shop wasn't too happy. At least they got a good used one
Shout out to Milwaukee for sponsoring the video 🔥😎👌
No bonus footage? That's your trademark!
Failure of the ecu internal supplys, i bet a smoothing capacitor was shorted.
Capacitors are a pain for going short.
Especially if they used tantalum capacitors.
Early 00s boards in general suffer from the bad capacitor plague, and with this 04 model year's ECU likely being manufactured in 03 or earlier it wouldn't surprise me at all if a failed capacitor were to blame.
@@JD-iu3vi Now wash your mouth out with soap & water lol :-D
I hate tantalum caps, designed to fail.
My only concern with this is are there any other 5 volt reference circuits leaving the ECM? If not I agree the ECM has died but sometimes there's more than one 5 volt output and they internally share the source. Also I'm not sure that using the TPS and EGR position sensors as a ground to a test light would be safe. Glad it worked out.
Coincidences do happen
Cut the wire and plug a USB adapter to it see if it runs if so put to a switched power source .
done on the cheap?
2004, the first real year Renault had their hands in design.
Walmart sells anti-glare screens for laptops.
Every video tells me to just ride a bicycle
I was hoping for a board resolder and burnt trace repair....no parts required but solder....
When the parts cannon is out of ammo and the car needs an ECM, that means the car's owner needs to put on those walking shoes!
How do these shops know to call you? Are you well know around your area as being the best?
Dang. Would have been real cool to have old ecm. Plugged in ecm without disconnecting battery a possibility? Why would they have unpluged it... Danggit
what kind of person throws away a bad ECM
Ivan, any plans to come back to Satan Island/New Jersey? I need diagnosis on a no spark on a 1984 911 SC
Possibly NJ trip in October. fill out a request form on my website pinehollowdiagnostics.com :)
@@PineHollowAutoDiagnostics Thank you!
👍