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

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! :)

Wow it's amazing how you are able to definitively pinpoint a fault like this. I watch a lot of KZfaq 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 KZfaq great, there is room for everybody!

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.

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!

Oh no! No Ivan post mortem. I feel cheated!🤣

Interesting....🤔

Bad shop we wanted extra footage they are always so satisfying to see

What a saga. Giving that one back had to feel more like relief than a win.

Great job once again, I love to follow your logic as you work.

Good systematic approach to diag nice Ivan

Ivan is fantastic. This is one of the few channels where I watch *every* video.

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

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.

Wow just love the way you think things thru!!! Great job Ivan! That's why the shop called you!!!

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.

Everytime if that ECM isnt putting out that 5V you already know!!!!! Great video brother!!!!!

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 .

It's going to be a tense moment plugging in the new ECM.

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.

Great job Ivan!!!

Great tip. Very cool. Thank you ivan

The smell of the magic blue smoke never lies.

Ivan what the hell?No bonus video. Quick video, I felt robbed.😁5volt ref is the 🗝️ thou.good job bro.😂

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!!

Cool diag. Thanks Ivan !

Thanks for sharing this nice troubleshooting tip.

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!

iVAN is a GENIUS !!! !!!

Another great video.

A little trivia: Did you know that one of the stars in the constellation Big Dipper is named Phad?

Ivan I look forward to every adventure. 12 volts on a 5 volt line. Hmmm I wonder about this. Another great job.

Top notch Ivan! I wonder what was the cause of it! Thanks for sharing!

Nice job and video like always

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.

👋Sir very nice diagnostic, I think the high voltage from the bad coil arc moving to the low voltage, truth a bad ground..blessings

Nice work!

Excellent tip

Like #799 Thanks for the video! Life is a learning curve! Hindsight is 20-15!

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.

You da man Ivan!

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).

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.

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!!!

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

Who the hell gave a thumbs down already. Scotty is that you

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.

An expert is someone you call in to take 50% of the blame when something goes wrong.

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.

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

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.

Great bother

Well thought out Diag... Maybe a post Renault/Nissan merge special

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 !!!

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

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.

He always does a great job!…lol

But.... Did you "do the grounds"!? LoL 😂😆

I bet that ECM has a nice black spot on the board, where it cooked a little.

Putting 12v+ on the 5v ECM output would make me nervous.

Had an o5 f150 today blowing black smoke out the tailpipe hardly running. Turned out power steering pressure sensor pulled the 5 volt reference

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.

Do you keep a Printer on your vehicle to print out all those wiring diagrams?

Would have been nice to do a dive into that box!

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. :)

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 🤔

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.

You first found that multiple modules did not communicate, but why did you check the 5v output in the first place?

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

👍

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 !!

Hello sir, good work .where do I get wiring diagrams for nissans

Shout out to Milwaukee for sponsoring the video 🔥😎👌

6:00 nice Ford Bumper.. looks like it did some of its job lol

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.

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?

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?

Someone hooked up a battery or booster cable in revers , that would certainly do it.

NO BONUS FOOTAGE!?

How do these shops know to call you? Are you well know around your area as being the best?

No bonus footage? That's your trademark!

bet the shop wasn't too happy. At least they got a good used one

Did Someone made a opps, how does a computer work then not after valve covers. Maybe disconnected the positive battery cable first and touched it too the body.

Dr's. bury their mistakes, shops throw theirs in the trash.

Mechanic initially reversed battery cables and tried to start it. That's my guess😁

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.

🤔🤔🤔👍👍👍

I was hoping for a board resolder and burnt trace repair....no parts required but solder....

2004, the first real year Renault had their hands in design.

Ivan, any plans to come back to Satan Island/New Jersey? I need diagnosis on a no spark on a 1984 911 SC

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.

Nice quick tshoot! Ivan, what do you recommend for a budget scope for a weekend enthusiast? Something in the $100 - $200 range.

My guess, bad distributor. Happened to me after replacing the. Verified it by the book and figured it out in seconds.

Coincidences do happen

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

Wont you damage a 5v circuit by putting 12v through it? Or is it because you are using the light bulb? I mean if the ecm was good if course.

Failure of the ecu internal supplys, i bet a smoothing capacitor was shorted. Capacitors are a pain for going short.

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!

Is it always safe to put 12v on the 5v output?

If that’s the only 5v reference output on the PCM, yeah bad PCM. However,, 😏,, another 5v output from the pcm would be ok and if need be, to a toggle switch lol.