Welding DISASTER... (Part 1 - No Crank/No Comm after Harness FIRE?)

This poor Chevy Cobalt has been a beached whale ever since the owner's son was doing some underbody WELDING repairs and the interior wiring harness CAUGHT ON FIRE under the driver's seat!!
It has been to another shop where the wires were patched up and the ECM and BCM were replaced to no avail.
Let's see why this rusty clunker isn't even talking to the scanner, and start peeling back the onion.
I have a bad feeling about this one...
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Enjoy the diagnostics marathon!
Ivan

[@paulmuff9883]

I was taught as a teenager back in the 60’s 1 disconnect battery 2 disconnect alternator/dynamo 3 check behind all parts to be welded for wires and carpets et cetera that could catch fire , such simple checks that would’ve saved him a massive bill and a headache but you as usual we’ll sort it out with your methodical diagnosis Carry on with the great work I love your videos I think you’re one of the best technicians on the net 👍👍

[@on-site4094]

If anyone can bring it back to life it’s Ivan. This world needs more Ivan’s is it worth putting all the time & parts into a 2010 cobalt

[@taylorsvilletony773]

No, it's not.

[@CrimeVid]

There is always some numpty who says it’s not worth putting the money into it (whatever it is) the owner however, has a different point of view. and who has the motor and the money in their favour.

[@mattbrown5511]

It would cost more just in parts than the car is worth to sell out right. Only if there were some sentimental value would the car be worth saving. I hope that answers your question. Be well.

[@baldyslapnut.]

If the cost to replace the car is a figure greater than cost of repair (factoring in hassle to dispose of old and track down a new vehicle), its economic to repair. Its not just about the book or scrap value of the existing vehicle. Not my decision to make but that's how I'd be doing my sums.

[@Bobbywolf64]

@@baldyslapnut. If you are very strapped for cash, 2k is a hard pill to swallow. However, you will not likely get a replacement car for that price. Most would abandon it, but I can still understand why some wouldn't. Is it a good choice? Nope. But maybe its their only option at the moment.

[@jerryking9544]

Awesome! dude should have kept welding until it burst into flames. He's gonna have more into this than it's worth just for this repair. Sometimes the juice ain't worth the squeeze.

[@johnt.848]

If it was insured he could have claimed on that after the fire.

[@garyalford9394]

Might as well junked it ! it is a colbalt !

[@tonster4]

man I did almost this exact thing in my 2011 Grand Caravan! We were doing welding repairs on the bracket that holds on the shock and it heated up enough to start the upholstery on fire! I saw smoke coming out and looked to see the rear seat was on fire! Couldn't believe it. Luckily nothing beyond the seat and the plastic in the back was burnt and it wasn't worse for the wear beyond that, but I couldn't believe it.

[@throttlebottle5906]

@@johnt.848 lol, the deductible would have been more then the payout. 🤣🤣🤣

[@cheeseo9798]

@@tonster4I had to weld a shock/spring tower on a 2018 Silverado, I put card board to block sarks from entering engine bay then right before welding I soak the cardboard with water. Along with disconnecting battery/grounds and ecus I could

[@tam1381]

Puts a new slant on feathering the throttle !!!!

[@PineHollowAutoDiagnostics]

🤣🤣🤣

[@lvsqcsl]

Just in diagnostic time, at 3 hours that is $450.00. You have it chased down and all it needs is module replacement. I was always taught you disconnected the battery anytime you are welding on a vehicle. I'll bet he watches where he welds next time. Great video!

[@larrybe2900]

That and keep the ground lead close to the area being welded.

[@pf-scottied0g969]

Well that was a whole box of surprises. I think it waited too long for the magic trick with the dove however. It didn't make it.😁

[@claytoncoolidge992]

I'm going to go out on a limb and say that he didn't disconnect the battery before welding

[@calholli]

Doesn't save you here. If he burned through the rusty metal and touched the wires with the welder, it applies that 20v to 50v to those lines, whether he has a battery hooked up or not. It's like basically hooking up a 50v power supply to your can bus line- It's not going to be happy either way.

[@claytoncoolidge992]

@@calholli that is the first time I've ever heard of that. Have any proof of this ever happening?

[@brianw8963]

That is a logical possibility. Lightning does travel pretty fast through safety devices before they disconnect, sometimes. Recently had to replace a fairly new big screen and a router and a couple other devices that were hooked to supposed surge protectors. I know that’s AC but actually a similar situation. 👍🇺🇸

[@claytoncoolidge992]

@@brianw8963 lol it's not logical it would have burnt the wires with the amperage of welding. Don't give bad ideas credit based on a completely different situation especially when you are talking about completely different types of things. Lightning isn't anything like welding besides the fact that welding uses an arc and there's no physical contact especially with wires with something between them most likely battery was connected and when a couple of wires got hot they shorted together and fried the computers. Here the other difference yous didn't work at all after the lightning these did just not properly and that would make it even less likely that some how the welder touched the smallest wire and fried the system. When you can clearly see the amount of wires that were repaired.

[@brianw8963]

@@claytoncoolidge992 OK👍🇺🇸

[@nes2123]

Good morning to all DIYER’s from Boston MA

[@brianzimmer1632]

Ivan let me start out by saying i'm a fan! I would recommend when cutting twisted pair to cut one wire at a time (when powered on and passing voltage) as basically when cutting both with metal cutters you are theoretically touching the two wires together and could be causing a short and causing more damage to components. I always try to power off the component and will only cut a single wire at a time. Food for thought for the extremely safety conscious!

[@Dave-ei7kk]

Brian, seeing Ivan cut through both wires on that circuit simultaneously made me cringe also. I think those CAN driver circuits are current limited and/or fuse protected. But as someone who has worked in both communication networks and power distribution systems I agree that de-energizing the circuit and if you can’t do that, at least cutting cutting one wire at a time is the best practice to follow. That said, I do acknowledge that Ivan is at a much higher proficiency level at this type of repair work than I am. So maybe he’s just learned through experience or some training that I’ve never attended that he can get away with this wire cutting operation on a CAN communication bus. And that’s why I watch this channel.

[@dans_Learning_Curve]

Made me think if cutting both at the same time was a good thing to do also.

[@earlribaudo4807]

Damage already done!!!!!!!!!!!

[@abdul-kabiralegbe5660]

Well, some CAN faults consist of the two wires shorted to each other, and this doesn't damage anything (as far as I know). All that needs to be done is trace the short and separate them. 🤷

[@PineHollowAutoDiagnostics]

You can short out the CAN wires all day long, won't harm anything 👍

[@JoeSmith-cy9wj]

I'll take the horse any time. It even has collision avoidance, antilock, traction control, self repair and maintenance, organic emissions, and it will get you home safely when you're drunk.

[@dans_Learning_Curve]

Funny!😂

[@JoeSmith-cy9wj]

@@dans_Learning_Curve It might be funny, but as far as I'm concerned it's going to be true. The video about the newly discovered round of solar flares expected to come will render the power grid useless, and most devices dependent on electricity. We will be back in the nineteenth century whether we want it or not. I don't know if we have a God, a guardian angel such as aliens, or are just all alone, but we obviously can't seem to subsist sustainability on this planet. So mother nature will have her way. And her way is change, that we are powerless to prevent. Sooner rather than later, either our own pollution, or her whims will come knocking. If you are into the ancient technology thing, you would accept that it has happened before. And our best science suggests it will happen again.

[@basshunter428]

I can tell you as someone that has done quite a bit of welding on vehicles (my 98 TJ has 3/4 of the frame capped) that you had better check the area you are going to weld in thoroughly! With all the electronic assemblies in the newer cars you have to be absolutely certain that the welding won't cause an issue. I also suggest disconnecting the negative battery terminal from the battery. Yes, you might get away with leaving it connected, but the time it takes to disconnect it as opposed to replacing/trouble shooting an electrical system is well invested. Great video, Ivan!

[@jdtractorman7445]

This is why manufacturers recommend disconnecting the battery when doing any welding to a vehicle. Lesson learned the hard way. Back when Ford was selling their Windstars there was a recall where welding needed to be done and that's what was recommended.

[@williamhague2768]

The feather pillow explosion in the muffler was priceless!!

[@bernardaflores1720]

The wife has some LOVELY horses!

[@mikechiodetti4482]

There comes a time when you just gotta let them go.....to the wrecking yard. You gave it a good shot Ivan! I know that feeling of not wanting to stop.

[@volvo09]

Yeah, I was hoping that car was destined for the scrap yard. That's hardly a car worth dumping 2k into.

[@calholli]

It's up to the customer. If he wants to pay-- just keep going.

[@volvo09]

@@calholli absolutely... At least it's being fixed right, whatever the reason. I just hate rust... If it was a southern car I'd support keeping it going. It's unfortunate that we can't easily ship rust free bodies up north, the scrap yards in the south make me want to cry watching solid vehicles get trashed, while up north running vehicles are trashed!

[@calholli]

@@volvo09 You're free to drive south and find a car/ truck and pull it back north on a trailer. That stuff is only really feasible if you do your own work. If you pay someone else to swap bodies, I can't image the price. lol.. But over all, I agree with you that it's not worth fixing this car if it has that many modules fried.

[@brianw8963]

Due to various circumstances we’ve all probably been in, sometimes You gotta work with what You have. Hopefully they come up with some used components and/or Ivan does some NPR magic or whatever . We will see! 👍🇺🇸

[@porky7753]

For Sale: 2010 Chevy Cobalt, sat in storage , may need a tune up, previously ederly owned.

[@kenoverton7918]

Only Ivan could have a car with feathers coming out of the tailpipe.🤣

[@jormalonnberg1578]

I think welder did two mistakes, 1. not taking battery of, 2. clear out inside for all flammable material. I learned it over 30 years ago, when my fellow student did not follow that rule, and burned interior of customers car. We were lucky our lunchbreak was only 30 min. and we could prevent whole place burning down. Avesome work Ivan , now Your customer knows what to do with it

[@volvo09]

Yeah, you are welding on a single sheet of stamped steel. Even thick steel will glow on the other side. Lots of cars have been burned by people welding on sheet metal that has cabin insulation and carpet on the other side.

[@brianw8963]

I’m sure the fella learned a valuable lesson, most of us have been down that road. I turned down 2 rust repair projects for just that reason. One on a otherwise beautiful older Buick and another on a Honda Pilot, just because I would have had to remove so much interior material to do the work safely. And I also learned by experience to be very careful working on rocker panels. That sound deadening foam they put in some of them must be impregnated with kerosene or something. Even a cutoff wheel will ignite it. Take my word for it!

[@jeffryblackmon4846]

I am surprised that the customer wants to complete the work. The exhaust bird was interesting. THIS WILL BE WORTH THE WAIT FOR PART 2. Thanks for the progress thus far! Hop on a horse and take a relaxing stroll with your Mrs.

[@abdul-kabiralegbe5660]

@35:05 - I love how excited Ivan is when speaking to his significant other, and how she just laughs all the time. 😂😂😂😂

[@jays106]

have little clue about engine and body electronics on newer vehicles but do find this very informative

[@calholli]

I bet he burned through that thin metal with his welder and actually touched some wires directly with the stinger-- and sent that 20v to 50v down the can bus. YIKES> That's a bummer.

[@jessicav2031]

Great hypothesis.

[@ferrumignis]

That was my thought as well, seems like the only way all those modules could be destroyed in one hit.

[@russellhltn1396]

Agree. I don't see how shorting the wires would do it, but add an arc welder and it's the start of a bad day.

[@simms196]

I'm only halfway through video & thinking replacement for all fried modules, wrecking yard might be a good place to start, excellent video 👍

[@Cheepchipsable]

He might try replacing with the originals, though I did skip ahead so I don't know if he tried that.

[@nickmalone3143]

I was thinking the same thing ...shotgun all bad modules with junkyard mods...but TCM you will still be SOL

[@craiggoodwin9704]

Okay? On to Part II. Thanks for Sharing!

[@ricfair9919]

GREAT Diagnostic work! Would of never thought so much damage could be done. I'm currently working on a similar problem, except the vehicle is a Mercedes!

[@titaniumman_22]

I can’t get enough of your videos. I love the thought process and how you explain things! 🇺🇸

[@ripcordres]

Love it.... "I hope he wasnt welding with the key ON"

[@brianw8963]

If it is do-able, it’s at the best place. Wow, this will be an adventure for sure. 👍👍🇺🇸

[@mrblonde2013]

Fantastic work, love your diagnostic path. I just about fell out of my chair when the feathers came out of the tailpipe 🤣🤣🤣. Is there a rabbit coming out of the air filter next?🤣🤣🤣. Cars with a low monetary value like this a are fantastic learning experience for guys like us, a great opportunity to sharpen our diagnostic process and learn new methods. Cheers.

[@baxrok2.]

I've heard this could happen when welding, though not due to fire damage. Definitely a junker. Great network case study Ivan!

[@rick5515]

I agree with everyone below. Was also taught to disconnect the battery and check for anything that will burn. Which I did last Summer when I replaced the left side floor pan and part of the right side firewall. No problems except I need to get my welding in order. More practice but, that is what seam seal is for. Hides it all. Thanks again for another great video. Off to part 2.

[@quicktastic]

Ivan, you are amazing for taking on projects like this. This seems like something where there isn't enough money in the world to make it worth the aggravation that is surely to come. Just watched part 3 so I had to go back to this to what started it all. What a nightmare.

[@williamkelley7654]

With the current price of used cars, we are in the unenviable position to fix what we have, even if the end results are having too much money into a car you already own. I have a 2010 Ford Fusion with really low miles but since I live in the rust belt it needs new rockers. Probably gonna cost me $2-3K, but I can't but a similar car right now for under $6K. We really need to market to correct, these prices are untenable.

[@mikedaugharty5544]

While working at the GM dealership before they closed in 18 we had a vehicle that had got hit by lightning and it took every module out of the whole vehicle every last one and this one had probably about 14 to 18 modules if I remember right and they were all toast and lots of work to program and put them all in there but they kept paying the money they didn't have they were self insured so they didn't have any insurance company to deal with so we just kept billing and billing and they kept paying and paying but probably should have jumped it over the head and the junkyard too but it is what it is not a good deal when the network gets hit good job there Ivan you are the man

[@Bellboy40]

The owner must have checked prices on getting another vehicle and decided that fixing this thing is worth doing. Vehicle prices, even used ones, have gone out the roof the last couple of years.

[@robertsmith2956]

Well, now that it starts it will make a good practice welding test bed. You can test for start after a weld. LOL Reminds me when I was at the shop and a man was working under the car, and knocked it into reverse with engine running. Drivers door was open and folded forward as car backed out the door. Tried to save a little money, and ended up destroying the hinges and panel.

[@Grayhook1]

The only thing saving it is replacing it with 1) A new car or 2)A used car that may have a can of worms hiding inside. Feathers…. My sides hurt 😂😂

[@roxanneabbott8424]

Wow a sad story for this car!!! Good job Ivan! Also nice to see you both have horses!!!❤

[@huntnfishnuts5880]

I think you had a case of welder current being sent through the wires into the modules. A fire at worst would have melted the insulation and maybe shorted to ground or 12 volts. The feathers in the tailpipe "priceless". Your right the horse is way more reliable. I have been noticing people spending a lot to fix vehicles a few years ago they would have junked, we can thank the stupidly high cost of new and used vehicles.

[@dustcommander100]

Gotta wonder if the welder had a high frequency start built in and whether the key was left on. Maybe his neighbor popped an EMP bomb, too! You're amazing - figuring out so much when the system has been "doctored" so much before you touched it. And the bird feathers flying out the tailpipe was simply amazing.

[@MyAdventures850]

Awesome job. Can't wait to see part 2

[@mod_incllc3235]

Great video showcasing your auto electrical prowess and amazing patience. You are the best at what you do and I wish you lived closer to Florida. If you ever make it down here or you know anyone in FL that rivals your electrical diagnostic skills please message me! You are the best can't wait to watch part 2!

[@jackiemay9471]

weld done with the diagnoses i thought you were flogging a dead one soon as we saw the modules offline i feel for the customer after all the cost from previous work thanks for video Ivan

[@dans_Learning_Curve]

Probably a typo, "Weld done", (well done) considering the damage was done by welding, I just find it entertaining.

[@jackiemay9471]

@@dans_Learning_Curve deliberate

[@dans_Learning_Curve]

@@jackiemay9471 LoL 😂😆

[@cpcoark]

If he has comprehensive insurance, I might be covered. Worth a shot

[@mikeburdi3464]

Awesome diagnostic skills!

[@cullenmiller8170]

Nice diagnosis and video. Definitely have to take good notes on this one. If my car ever catches on fire I will fan the flames and hope the fire department doesn’t show up until it’s a full carbque. 😂😂

[@cwstout1]

The tailpipe module should have detected the bird, but of course it was fried also.

[@cyberslacker5150]

I think the 30 volts from the welding machine is what fried these modules. In CAN wires I've had them shorted to ground, shorted to positive, shored to each other, and shorted to other wires and the modules don't get fried. Usually the CAN lines are made to be resilient against shorts. As long as it's 12 volts or less it's OK, but 30 volts is too much. You could go to a cheap Pull-your-own-parts type junkyard and buy the modules off another car and flash them. Buying them online would cost too much. Also, maybe flashing the PCM would fix the throttle body. You should scope the throttle body motor leads, see if its the PCM or the body that's bad.

[@htownblue11]

Wow. This case was bizarre right down to Ivan evicting a bird from the tailpipe promptly. 😂😂😂. I told you guys Ivan was a wizard, now he makes birds disappear.

[@eduardofrederico]

Excelente. Gostei e aprendi muito. Parabéns!

[@justbob999]

They say you learn from your mistakes..this one was expensive for the owner. But could have been worse...My lesson involved a marriage license.😂

[@rodneymiddleton9624]

Great learning video!! Thanks!

[@renerivas3619]

Good morning every body from California. 👍have nice. Weekend. 🙏🏾ivan

[@vpimike2646]

Better yet Ivan, he should donate it to a tech school for a restoration project challenge.

[@volvo09]

I don't even think they'd want it.. unless it was for freshmen to practice body filler on. Rusty commuter cars are all over scrap yards, not exactly hard to find. My school didn't take old beaters, it had to have some redeeming quality to it.

[@martymurphy9627]

That would be frustrating!

[@billmonroe8826]

To all welders out there, even before electronics were on cars you always disconnect the battery. Now you disconnect everything electronics also. What a nightmare for the owner! 🙃

[@weloveups831]

Wow! Can't believe it didn't catch fire as in engulfed! Which might have been for the better if he was welding outside away from the homestead!

[@str-lrd3863]

That car had other issues before the burn. At 21:30 you can hear the engine galloping on crank over. One or more cylinders has a mechanical issue.

[@dans_Learning_Curve]

Best footage was that of the horses and your wife! It's good she shares in your small victories!

[@AP9311]

Wow, that was a pile of problems!! But i have a feeling you'll fix the Russian repair and do the minimum fixes and get it running etc, enough to get a beater. Great job, Ivan!

[@warrantyvoid100]

Anybody else waiting to hear Ivan say "So I bought it off the customer and we're going to fix it up as a shop beater"

[@xanderlander8989]

Looking forward to part 2!

[@CactosS]

huge plot twist at the end

[@billsmith2212]

I know the Wilberts Salvage Yards near South Main Auto are cheap . Maybe you have similar places in PA . Sometimes a complete wreck is the way to go . Then junk it again . They generally don't care if it's being shredded .

[@senanfoutchedjev2401]

What. Part 2. Man some people do really get attached. Man. Thanks.

[@advancedleveldiagnostics]

Great video Thanks!

[@charleshenshaw9099]

Sometimes people throw good money at bad things. This is one of those things.

[@travissheehan6082]

The feathers was classic

[@donb1661]

If you are able to fix it, I doubt he could purchase a more reliable vehicle for anywhere near the repair cost. He is getting extra value having you do the work.

[@pcallah3442]

I've seen it all now, feathers out the exhaust, something foul going on there.

[@pingpong9656]

Owner must have been kicking himself after that mistake... we've all been there in some form.

[@throttlebottle5906]

unhook battery, remove carpet and everything flammable within a foot of where you'll be welding and anything electronic in a three foot radius. then start welding, it doesn't hurt to wet the areas around the weld to help keep paint from burning as bad.

[@Markb8608]

Hi Ivan. Its Mark with the 400k mile vw tdi. Good show on welding. Was it thecwelding current or fire itself that caused the issues. I was wondering if he was using a high frequency tig. I am a novice at welding but recently went out and bought high frequency tig welder to repair cosmetic body panels. Little did I know that it is not recommended to use high frequency around the pcm or sensors. So I threw 2k down drain. Your video makes me feel a little better about not welding with high frequency. Great diagnosis.

[@thatsonebadhatharry8610]

If you are concerned about the electronics just unplug them before you start welding. Isolation should stop any unwanted voltage spikes damaging them.

[@hightttech]

I missed the fried chicken 🐔 the first time i watched; FEATHERS! 😂

[@riverflyswatter]

Wow! Good video

[@jays106]

the guy that welds on my truck always says to unhook the ground cable from the battery whether doing body work welding or frame welding

[@petepeabody8905]

This customer must really want their car back and must have a shit ton of money to make it happen. Without Ivan at the helm your odds are greatly reduced

[@mattbrown5511]

This video shows the power of EMF/EMP. Always make sure your work area is clear of ALL wiring and electronics if you are going to weld on a working vehicle. I have seen this happen before (No, I didn't cause the damage. A friend caused $4000 worth of damage to his car.)

[@jimmartin9440]

Good morning, from the San Francisco Bay area.

[@noelcastle3986]

Sometimes you just need to walk away from a potential money pit cut your losses and move on. How much rust is in the underside that required welding and repairs. That relay not being plugged in threw a curveball . Looking forward to part two glad its not me paying the bill.

[@HouseCallAutoRepair]

Wow, that's a workout!

[@richleyden6839]

Best footage, feathers shooting out the exhaust. A KZbin first!

[@mike-yp1uk]

Check the starter relay because the pin in the box goes bad a lot. Lol

[@mikefoehr235]

The best part was watching feathers being spit out of the exhaust. God that was funny. Looks like Amanda enjoys her horses. Fixing this car is nuts. Get a Corolla or.Civic same age...be much better.

[@neilmurphy845]

That is correct

[@tomtke7351]

good lookin horses.... And healthy! Ivan is likely TEACHING techs all over the world.thru these videos....

[@billsmith2212]

Looking back to the beginning , too bad you couldn't get a complete wreck to source parts . If this sat a while , what condition is the gas ? The gift that keeps on giving .

[@beaverc2884]

Bird feathers shooting out of the tail pipe, I doubt any of us have ever seen that before. 🤔😅🤣😂

[@brianw8963]

Not a tailpipe, but had a blackbird in a flue pipe for a furnace once. That was a mess. 😄

[@stevepark5504]

The throttle body was evidently working when you were revving the engine for the tailpipe show. What makes you think that it is now not functional.

[@geraldharkness8830]

sad end but how far is enough!

[@charlesadams41]

Feathers!! 😂

[@leeross7896]

I am not a welder, what is the proper way to weld on a modern car? Batt disconnect I am sure but after that? Is it as simple as establishing a good ground right next to where you are welding or does more go into it than that?

[@volvo09]

If the arc happened to strike the communication lines then I don't think anything can help you... But I would like to hear proper practice. I'd at least do what you said.

[@nickmalone3143]

With an arc close enough you can get a current spike just with induction

[@simonjones7785]

chevy been taking lessons on wiring from the dreaded PSA Citroen Peugot Renalt group

[@northernpatriot9078]

the ole rust repair welding trick yep every time

[@electron-1979]

If the short was rear of the burnt wires, the current would go to the rear but not come back on another pair 😂

[@danieledesimone609]

Hey Ivan do you think you could explain how you were jumping power to pin 6 and 14 through a test light to determine a short to ground condition? I'm understanding it as adding a load in line to verify when power is jumped to the circuit it is finding a ground, and lighting the test light. But what does the 1.2 V mean once it's jumped? Also does the test light in line limit the amperage going through the CAN circuit to only 300mA, protecting the computers and the 12v reference circuit? Thanks in advance!!

[@calholli]

It just means that it's not an absolute short.. Because then it would say 0.0v.. So it's a partial short-- which could be through some weird corrosion and green crusties-- or in this case, it's likely shorted inside modules where there are a lot of electronics and circuitry, so you still get some voltage readings. --- Now I could be wrong here, because I'm still learning about can bus just by watching. lol.. I agree that it would be super helpful if Ivan would have explained what pin 6 and 14 "Should be" on a known good.

[@hightttech]

1. The test light does limit current to ~300mA. 2. The 1.2V tells us that the ground is not perfect. If you probe to "perfect ground" (like battery negative post), in theory you'll measure zero volts and test light will be bright. In reality, you might measure ≤ a few millivolts. An extreme example would be a nasty battery clamp causing a "NO CRANK" complaint. You'll notice during initial testing that headlights go dark when key turned to "CRANK" position. If you measure voltage between offending battery clamp and battery post, you'll measure SEVERAL VOLTS. Clean and tighten your clamp, and you should measure only millivolts during cranking, and headlights will barely dim with a good battery.

[@danieledesimone609]

@@calholli ahh I get it now. We're not seeing all the voltage get consumed across the load. Almost like there's another load in the circuit, potentially in the form of corrosion, that the remaining 1.2v would drop across. Thanks!!

[@calholli]

@@hightttech RIght. The bad battery terminal connection acts like a resistor and will have a voltage drop across it, typically up to 6v; (like a voltage divider).

[@danieledesimone609]

@hightttech Yea I got confused and needed to look at it in terms of voltage drop across all resistors in a circuit. In reality there's another load somewhere in this circuit. Like the battery terminal example you gave. Simply measuring voltage drop across the terminal. Makes sense. Thanks for taking the time to clear things up for me!

[@cliffyb5896]

Question is, how long was the CEL lit up before the owner almost burned it to the ground.

[@mykofreder1682]

Welding is an electrical process messing with the ground of the vehicle, I think they tell you to disconnect the battery and make sure the positive is in the air when welding. You get current and odd voltages going through 5 or 12V digital components, bad things might happen, eliminate the current path and it shouldn't be a problem. You put those voltages directly into the wires, all bets are off for those modules regardless of what you do with the battery and car 12V circuit.

[@mrbuilder2k99]

Good morning Sir. I did a double take when You said "Feathers"? Take care.

[@calholli]

You can read amps while clamping both wires? I thought they would cancel each other out, and you can only test amps with a clamp across either positive or negative- but not both at the same time?

[@anameisrequired3729]

Only if the return current flows on the second wire. In this case, the return current likely flows on the chassis.

[@Eastahtata]

Both network wires were pulling current with the bulb in the circuit, so clamping both just gives you total current draw.

[@markrup6115]

I was suspect of your original diagnosis only because the VCIM showed to be on-line.