I think you are right about a reverse jump start... Alternator shorting out is pretty much guaranteed, and if that's all that goes bad you get lucky. Must have been a real competent shop that did that work :)
I personally do not remove the battery cables when welding. The problem is not that they leave the battery hooked up. The problem is that they do not put the ground in proper location. Say your welding broken exhaust manifold bolts. You have to put the ground on the head itself. Not the engine block. If your welding exhaust it has to be on exhaust close to what your welding. If you ground something else and then the current finds its way by any means possible and the result is what your dealing with.
I watched someone weld a REAR shock perch under a Lincoln. He hooked ground wrong and set the master cylinder under the hood on fire. He put ground where it grounded through brake lines. The lines are insulated from front to back with little plastic retainers to the car body. I have seen some weird stuff.
Not so sure about that. Not saying your method is wrong, im saying modern integrated circuit technology is waay more fragile than you think. Semiconductors are vulnerable to certain frequency and high voltage spikes. When you are arcing and sparking down there, those sparks are actually very high voltage spikes lasting from milliseconds to nanoseconds. These spikes have electromagnetic pulses that radiate outwards and can randomly induce currents into unshielded circuitry. Worse case you blow up a circuit. You could also be injecting minor damage to semiconductor material..damage known as " latent defects" a latent defect can be physical damage to semiconductor junctions in transistors diodes, mosfets, and others. This latent defect may not disable the circuit, but degrades the component and decreases its reluability or lifespan. All semiconductors have limits to outside electrical impulses, feedback, arcing and sparking..can only take so many zaps😢
I can tell you that I work on modern cars and obviously not welding a rusty exhaust on a 2018 but in my experience I have never unhooked a battery to weld an exhaust. I am also using a newer welder that is inverter I think. I am using a dc mig process. Welding with an ac flux core welder may be different because it uses a higher voltage. I guess I could have clarified that depending on the process and voltage used. Actually leaving battery hooked up IMHO is better becasue the battery can act as a sponge to soak up those currents. Again if you ground it properly I think it doesnt matter.@@pootthatbak2578
The second you were able to determine that the short was through the module instead of the wiring (and multiple failed modules) I immediately figured there was a reverse polarity event in the car's past. Glad to know that everyone seems to believe that as well.
I saw it on many chryslers. PT cruiser came in, no start. Needed a battery to start, Determined bad PCM. Why? he hooked battery charger backwards to charge bad battery. I did the diag, and the repair and advised he needed a timing belt too. He declined. Had it towed in 2 weeks later for a "fuel pump". Just quit on the highway. I checked, yep belt broke, Not a fuel pump.
I was feeling pretty good about tracking down a broken wire on my driver's door power window...until I see you taking a car that is totally dead and systematically disconnecting and tracing circuits and finding out where the problem is, or multiple problems are. Cars have gotten way too complex for Joe Shadetree to diagnose these things anymore. Love watching your videos.
The replacement alternator was the evidence needed to indicate a reversal of polarity. So easy but so disastrous. 3K and no wheels is getting serious. Very good auto detection work with no traceability to hand. Feel sorry for the customer but made the right call. All in all, a very satisfying result with a minimum of tech.
If a shop caused this by jump starting it backwards then shame on them, mistakes happen but you need to have the integrity to acknowledge that you made a mistake and make it right. I started out working as a mechanic and I made mistakes but I acknowledged them and fixed them, after a while I decided that I didn't care for life on a creeper and got into building trades. I made mistakes there as well and again I acknowledge them and fix them. Hiding a mistake is no different than stealing in my mind. My customers don't pay me for mistakes they pay me for a properly completed job. When I train newcomers that is what I drill into them. And to reinforce this I am brutal in critiquing sloppy work, especially sloppy shortcuts by supposed "professionals". I want trainees to have a sense of pride in their work, I want them to dread being shamed.
Many years ago, I dealt with an E36 BMW which would not shut the engine off when the key was turned off. Everyone where I worked said ,"Oh, it needs an ignition switch. Just order one. Why are you still trying to diagnose it?" Half an hour later or so, I determined that the instrument cluster had an internal short between a "hot in start/run" circuit and a "constant battery power" circuit. A replacement cluster fixed the issue. There was nothing wrong with the ignition switch. It's a shame so few technicians understand how to do this kind of diagnosis.
Great video again, 1st thing I thought of was a welding spike. Your fault finding is once again exceptional, and your suggestion of a jumper pack issue spot on. one way to sometimes prove a battery live and negative swap is to look at the wiper motor, they automatically run backwards on a misconnection, this breaks the parking contacts in the wiper, the result is that when hooked up correctly the wipers won’t auto park when activated.
If I ever have a similar situation I feel after watching this video I can confidently attempt the diagnosis myself. Just one little caveat II All I need is notice of when you will be in the Tidewater Area of Virginia to fix what I end up destroying in my attempt.
That’s a shame, I would have love to see the final repairs and car start and drive. But after 1 year and $3000, I can’t blame the owner for not wanting to spend any more on it. Great video!
Personally I think the owner's an idiot. A person spends $3,000 on suspension because they intend to keep that car as a long term proposition. After being told "NOW that we've taken it to a COMPETENT repair shop (that calls in PGAD if needed) we've fixed most of the other problems except it needs 2 new computer modules, used ones probably cost $400 and it will go for sure". To which the owner goes "No, scrap it". So it's cost him whatever money he had in the car, plus the $3,000 for a whole heap of suspension work, plus whatever other costs, but for not wanting to pay $400 more, he's gonna sell it for scrap for like $1,000 ? Maybe "Samcrac" or "100% Jake" will buy this at auction having paid just a thousand dollars for it , find out it needs just a few hundred dollars of used computer modules and have a great running new 4 wheel drive waggon for the Winter, and hey, brand new alternator, no flat batteries on snowy days LOL. Note when Samcrac gets a snowy day, we'are all in trouble.
Ivan thanks to your patient trouble shooting example in all your videos I managed to diagnose a no heat condition on my car that cost me nothing more that a new ratchet set to fix. (turned out to be a tired heater valve) I would not be able to charge by the hour like you for many years but the money that is still in my pocket is much appreciated. Thanks!
Great use of the test light instead of blowing fuses.... Best lesson I have learned from you so far... I'm building a collection of test lights for my toolbox.
Wow! So, this customer is out 3K and gave up on the car? I can only assume that this shop wanted to charge the customer for their incompetence. As I see it, the shop that caused the damage to those modules when they jumped the car wrong, should be liable for replacing said modules. Not the customer. That's crazy.
Though it was not a good turnout for the Mazda or the owner, it was very interesting and a great lesson. Surely there is a u pull it somewhere with the parts if someone had the time and ambition, but it is what it is. None the less , great stuff as always. Nice work Ivan. 👍👍🇺🇸
this is what we THOUGHT happened to a Jeep I bought last October when I went to have a new battery put in. that same Jeep *is what started me watching all you guys' channels!* turned out a popped fusible link (which i didn't even know they were *still using in cars*) saved all the electronics. the only casualty was the radio fuse. unfortunately, said Jeep, which I just saw today at work, needed more mechanical work than electronic work...and no one will touch it becuse of its age and mileage.
Great story with not so happy ending for the owner. 3K and my car goes to the junkyard? You can't always win. So hard for people to find a reliable repair shop. Worst part of owning a car or truck is the maintenance and repair nightmares.
Yeah I do all of my own work on the family fleet, and there's definitely times I get stumped and would prefer to take it to a professional. But then I remember some shoddy dealer work done to my car before I bought it, so I just press on the best I can.
@@michaelgleason4791 Iam lucky that I am a retired mechanic but now with the new vehicles I sometimes struggle & Iam lucky to have a great mechanic to bend his ear for possible causes & solutions.Got a dead one in the gutter at the moment ,been raining so Iam sitting impaciently waiting for the rain to stop.Cheers.
Good job Ivan. Every time I think about getting rid of my gas hog 2004 Sequoia i watch one of your videos. Yes its heavy on gas but I spend zero on anything other than (gas), and parts for routine maintenance. 180,000 miles and pulls like a train.
For tracking down dead shorts, or open wires I've been using a Fluke pro 3000 probe and tone generator. It sends a signal into the circuit, and follow along with the probe to see where the short or open is. Using a amp clamp, the conduit has to be opened up, and risk making the problem go away.
Really great case study Ivan! I like how you used a test light I place of the fuse to chase a short to ground. I’d assume some circuits depending on the load can potentially light the bulb but for the most part this Is a great tool for the Arsenal thanks for Sharing!
The first shop sounds like a backyard setup simply because any registered place of business should have checked the polarity berore jump starting the vehicle even if it was an apprentice someone at a registered business would have checked that persons work.I know that when I was doing mine (apprenticeship) that was one of the first things drilled into me CHECK YOUR TERMINALS BEFORE ADDING JUICE was my teachers comment everytime I went to jump a vehicle.Cheers Ivan.
When you got started I just knew you were going to find a pinched wire from the other repairs. I have had to snoop out pinched and welded wires in the past (no fancy scanners, just s Power Probe and a little knowledge).
Jajaja let me just mention a few of the common problems on these Mazda #1turbo assy #2 vvt actuator and timing chains #3 transfer case leaks and noises #4 rear diff leaking and noises #5 timing cover leaks And so on Thank god they stop making it I work on Mazda for the past 24 years and I never saw a Mazda with so many common problems . Great diag Ivan And good decision by the cust when he decide to scrapped
I havent seen that so much for Mazdas, but i have seen it on Chryslers REPEATEDLY. Had a 4.7 dakota come in. Customer drove it home, shut it off, wouldnt start again. He took 7 shots with the parts cannon to the tune of 1000$ in parts. Cranked it until the battery was dead. Tried again a week later. Then towed it to us. I tried to scan it, no communication. Checked powers and grounds. Bad computer. Replaced computer, I could communicate, but still no start. I started a second diagnosis, Checked data, cam/crank sync data PID, said no sync while cranking. Scoped the cam sensor, no signal. Put a sensor on it, fire right up. That truck needs can sensor for starting ONLY. It failed, didnt know it until restart. Customer had hooked up jumper cables backward and turned on the key. Fried computer. My diag an repair was only 500$ He threw 1000$ at it in parts hoping. He changed everything he could see, But that cam sensor is below valve cover on right side of engine out of sight.
Yeah, if you don't pay close attention to what you are doing you can easily add in variables that are tough to figure out. A few weeks ago I pinched a wire on an oil pan job. I though it was an intermittent problem flaring up that got worse, but it was my doing.
I did that putting a transmission in a stretch limo on the ground. I was much younger then. I caught an O2 sensor wire between engine and transmission.. It was harness side, so yeah it sucked.
Great video Ivan as always. Next time you run into something like the owner want to get rid off it lmk cuz specially after the great diag that you did what is left is a pice of cake . I will buy it no question ask I will fix it . Thank you sir
The wiring diagrams are available free online as PDF's for viewing or download. This won't help in your using your electronic diagnostic gear but they are there.
Ivan { you are A Genius } I sure hope the customer thanked you for your proper diagnoses. but What a shame and waste from making a big boo BOO of reverse connection from the first shop which should be held responsible to that customer ...
I have had 2 Nissan's in the last month that a bad battery caused this much damage. I was lucky with only ECM's with both, but welding marks on both vehicles battery terminals.
I add a car like that,after about 9 hours of work got it back to life,my car was jump starter reverse polarity,it took out tcm,burn a few wires and a feww fuses,it was a honda civic 2019,was at a body shop
Great diagnostic, Ivan! Most junkyard cars look more pristine than that Mazda. Great effort, only to be thrown out by the customer - why did he wait so long to make a decision. I think the first shop has a big responsibility - they created the problem but, after a year, how is customer going to complain? A serious diagnostic does not always lead to a happy ending.
Maybe it was a play thing purchase & the owner was working on it when he had money but Iam pretty sure he was not prepared for someone to damage it that badly (reason for this comment it was a turbo).
Ivan, great work again… Surly it wasn’t up to the customer to say ‘scrap the car’, it should have been the garage who caused the damage in the first place to make it right. By scrapping the car the garage who caused the problem has got off ‘Scott free’ …. Must admit… I would have been tempted to remove the module and check them on my bench back at the ranch. Just for the hell of it. After all if the car goes for scrap it wouldn’t have mattered if a few modules were missing would it!
Unusual for a Japanese model to suffer such damage from a reverse polarity jump start, normally they are well protected and can survive without major damage. Interesting as always, thanks for sharing.
My buddies truck was here at my shop for 2 years. No puddle of oil under it but when I started it it was making racket. Ended up 2 quarts low. Always best to check it first. Hindsight.
Why did the owner go that far and give up? Were the modules that expensive? Did the original shop repay any money to the owner? Lots of questions..............
Such a simple approach its mindboggeling.Thanks so much for your videos. Geat benefit to DIY professionals. loL Are you getting the new updated thinktool pros?
Some devices have reverse polarity protection. I wonder what it would take to do it at the battery before it hits the fuse block or at the fuse block / TIPM before it hits the branch circuits.
At 20;36 And knowing that they changed alternator my guess is Shop hooked battery up backwards and blew out some electronics Watching the rest to see if I get it right I’d bet radio is also doa Probably a diode in transmission control
I guess you have to be careful doing any kind of welding on these newer cars that are filled with modules. Any time I've ever had to do any welding on a vehicle I always make sure I have a very good and clean ground with the welder, and that it's placed as close to the area I'm welding as possible to keep any voltage spikes from getting somewhere they shouldn't be. I'm guessing that Mazda was rusted out pretty bad and needed some structural repair to keep it on the road. I'm glad I live in the south far from the rust belt.
U should have borrowed it before it left for scrap and stuck the tcm in it. Though it should be able to be bypassed as the only thing that it's missing from the tcm to atleast start is the nuteral safety switch so should have been able to supply 12v to the starter and seen it crank if not start and run
Most car computer are failproof or will report they are bad, I live in a poor area and get the reverse polarity all the time. Sad to tell them what they did, but facts are facts.
Maybe the owner struck a deal with the original shop for all or part of the repair cost and then he wanted to see if it was a cheap repair to get it running ,then decided to junk it.
Great video Ivan, please take some time and explain your test light in more detail and where you get the connectors. Are those from a power probe? Thanks!
There 4 components that can cause similar issues that I'd disconnect 1 by 1 ABS unit Alternator feed Starter feed Bose amp feed The biggest issue with the cx7 turbo is the Big end journals going bad causing a zoom zoom kaboom fault .
I'm kinda sad the Mazda didn't get fixed. Given the time period that has passed, we don't know the struggle the owner has already endured trying to get to a resolution. Now with this new info the customer knows it's going to need at least those 2 modules, which still won't guarantee that it may need even MORE $ spent on it to get it fixed properly, they may have decided nope, they can't handle the stress of it anymore in their life and cut their losses, dumped the vehicle, and have moved on. 🤷♂️
You just don't take your car to any car shop to replace parts. Now you can go on line to learn how to do it yourself to save money. If the owner did not replace the suspension system the car is still running now.
