noise."MECHANIC: What I got for Christmas at the Shop! (part 1) · 3:15am January 12th
So I already told you what I got for Jinglemas, but let me tell you what I got for Christmas (and New Years) at the shop!
Fair warning, those of you who are used to my normal mechanic blog posts where it's a mystery until the very end, this one was not a mystery for very long. Fixing it on the other hand . . . well.
There was a book my grandpa had full of cartoons of would-be woodworkers, and it was titled Sure You Can Do It Yourself. This will be come relevant, too.
Now that I've lured you in, make sure to grab a glass of your favorite imbibement and settle in.
The vehicle in question is a 2017 Ford Explorer with an engine (I legit don't remember which one). A tow truck dropped it off sometime before Christmas and in the usual fashion of our wrecker drivers, instead of putting it into a parking spot, he just left it in the middle of the lot.
Come closing time, we need to pull cars into the shop/across the lot, and of course we can't leave this thing in the middle, so my manager sent me out with a jump box 'cause the customer's complaint was that that alternator wasn't charging.
Fair enough. I grab the jump box, and just in case there's enough charge left in the battery, I try to start it before opening the hood.
The first thing I notice when I open the door is that the interior lights don't come on. It's a pushbutton start, so I push the button anyway, not expecting anything to happen. The engine starts just fine, though. Weirdly, the instrument cluster doesn't come on, and neither does the radio; none of the backlights for the various buttons and knobs come on, either.
But it's running. Likely not an alternator problem, but who knows. Point is I won't have to push this dumb thing, I can just drive it into a parking spot.
Or so I thought, until I shifted it into gear and it started moving and then it stalled.
Could be the voltage got too low, maybe that's why none of the interior stuff is working . . . but then it fired right up again, went a few feet, and stalled again.
This is also when I noticed that it was difficult to turn.
I will never get tired of this image
Those of you who are familiar with cars back in the day will remember if you had power steering and it didn't work, it was really hard to turn the wheel at low speed. If this were an older vehicle, I might assume the belt had come off; that would make the alternator and power steering pump not work . . . however, this has an electric motor for power steering, so it's not one failure causing both problems (as it would later turn out, it did have two problems).
A few more attempts to move it all ended the same; even if I didn't shift it into gear, it wouldn't run for more than thirty seconds before stalling. Hooking up the jump box didn't help; it's not a voltage problem.
[In fact, it was, but we'll get to that.]
So I resigned myself to pushing, got our lovely assistant, and he noted that while it would turn right okay, it really didn't like turning left. He also thought that an electric rack without electric assist should feel like a manual rack, which I also thought but hadn't really processed through in my mind.
I tried the steering wheel again, and now it was almost completely locked up when turning left, but went freely to the right. Broken rack? We've seen that before, although how the customer would confuse that with an alternator is beyond me.
The rack was not broken. I gotta take you back in time a little bit, back to before this car came to us. The customer had noticed that the alternator was not charging. While there may be a gauge that will tell you that, on this particular Explorer the message center on the dashboard would also tell you that: it would chime, say "Service Charging System" and also turn on the battery warning light for good measure.
This vehicle used to have an aftermarket remote start. For those of you who don't know about them and/or haven't read previous blog posts of mine about them, you can buy a little magical box that is spliced (usually badly) into the vehicle's wiring and if all goes well, you can click a button on the remote that came with that box and your vehicle will start itself while you stay in the comfort of your home.
Time marches on, and on this particular Ford, instead of something that's spliced into factory wiring, somebody got clever.
These days there's a whole lot of different networks on the vehicle (this Ford has at least 2 high-speed CAN networks, a medium-speed CAN network, maybe a couple of LIN busses) and they've all gotta communicate with each other. Typically, there's a module to translate called the Gateway module. Ford decided that since they also needed an OBD-II connector [this is where you plug in a diagnostic tool] which attached to various networks, why not make the OBD-II connector into a gateway module? So a whole bunch of network wires go into the back, it does its magic on the network and also talks to the scan tool.
That's a really smart design by Ford [don't ask my about Daimler Chrysler Fiat Chrysler Stellantis' secure gateway module that has all the features of Ford's, but locks it behind a paywall].
And if you're an aftermarket remote start company who wants to build a little plug-and-play module, you could have it plug in right there, and you'd get all the networks you need for your module to work. All you need is a little jumper harness.
So our customer had decided that the remote start was bad, and he just unplugged it. Problem solved, job done. Except that didn't fix the alternator. It also meant that the gateway module couldn't communicate across networks and if that was the only problem you'd have read about this disaster.
Most of y'all probably haven't been under the dash of a vehicle, but if you had been, you'd notice that all the wires are neatly tucked away in looms which are fastened to various secure points in the vehicle. This is to keep them from chafing on stuff or worse, getting caught in something. Like say the steering shaft, which runs down from the steering wheel and through the firewall.
(This was taken from basically the floormat looking up; the connector on the middle left is the one that goes to the gateway module . . . obviously it should be plugged in. If I'd hooked a scan tool to this Ford, I wouldn't have been able to communicate with any module. I hadn't (yet), because sometimes the Mk. I eyeball is as useful a diagnostic tool as a fancy electronical gadget.)
I didn't mention earlier, but not only had I discovered that the steering only really worked one way, it also made weird noises when you tried to turn it the other way, and I also discovered that pushing the button for the hazard flashers made the starter engage.
Yeah, that little tail from the jumper harness that he'd unplugged and then not secured had not only rendered the gateway module useless, but it had also gotten caught around the steering shaft and started to pull wires apart, and I had to spend nearly an hour in a dark parking lot, on my knees, disassembling the dash enough that I could untangle the wire harness from the steering shaft so we could push it into a spot.
There are some jobs that I do not look forward to. Weirdly, this was one that I was actually excited for. It was such a disaster and going to be such a time-consuming fix that I was actually getting excited to work on it.
Why?
Well, for starters, there's what I can already see: wires wrapped around the steering shaft, wires pulled out of connectors, broken connectors, things shorted together that shouldn't be.
I also knew that what I was seeing was likely only the tip of the iceberg; the deeper I got into it the worse it was going to be.
There was also a very high probability that when I fixed everything I saw that was wrong with it, I'd put it back together and find other problems (the broken wire I didn't see [spoiler, that happened, sort of]). And when everything was all fixed, only then would I be able to diagnose the problem it had initially had.
We pushed it in the shop right before leaving for Christmas, and when I came back the Thursday after, I got to work on it. A few more parts needed to be stripped out to get me full access (including the steering column) and as I was playing with chewed-up wires I tugged on a data line that seemed loose and it fell out, indicating a break far above what I'd seen so far, and this is where the full scope of the disaster manifested itself.
The main under-dash harness mostly runs along the support bar under the dash. On the driver's side, it's attached behind the instrument cluster and ducting for the left outside HVAC vent. Then it drops down to attach to the fuse box, the gateway module, and two body harnesses. As it had wrapped around the steering shaft, that corner had acted like a knife and sawed through about half the wires in the harness. To Ford's credit, the airbag wiring failed safe; while several wires were cut, none of the airbags went off unintentionally.
(You probably can't see much in this image except that the tape is rubbed thorough . . . trust me, bro, there's a catastrophe behind that metal support brace.)
[Also as a second aside, that blue scrawl you see is an inspector's sign-off or some other kind of factory marking—it's the kind of thing a customer never sees but I do on occasion, 'cause I get to go places in your vehicle you've never seen.]
[As a third aside, that big plastic piece above the wires and the metal brace is the duct for the left outside HVAC vent—now you know what those look like!]
[As a fourth aside, I used to work in a plastics factory that made various pieces of vents and ducting for automakers (among other products). We had a fancy robot machine that wasn't very good and often needed a human employee to do its job for it, and we also had a really fast machine that made the little thumbwheels you might have on your vents, to turn them or to shut off the air. Another made short duct pieces, and the operator (me, one day) got to put a little strip of self-adhesive foam insulation on each one that the machine spit out.
[If you have a car that was built between 1996 and 1998, or a Subaru Outback built mid-2005, I might have worked on it, or some small part of it.]
[As a fifth aside, you see the tiny space I'm gonna have to fix this repaired harness back through]
Due to the nature of the damage, I had to cut out sections of every affected circuit and splice in short lengths of jumper wire. Since we didn't have any that was the correct gauge, I had to use various lengths of wire we had left over from other projects.
Also, getting the harness to where I could work on it was a chore; my manager didn't want me to take out the dash so I had to partially disassemble a couple of connectors to make them fit through a hole they shouldn't have fit through.
I spent about fourteen hours soldering wires on this disaster. Late on Tuesday, I finally got it put together enough to plug everything in and power it on—just for giggles, I pulled codes and it had sent 78 of them (unsurprisingly, all communications or circuit codes) across various modules. These were all faults that happened before I started working on it.
Clearing the codes and then scanning again, I had a few expected ones, and nobody who wanted to find the radio could. Unsurprising; when everything else lit up on the vehicle, the radio didn't.
To my shock, it wasn't a wire I missed while I was repairing; instead, at some point while everything was shorting out, the fuse for the radio had blown.
At the point of writing this blog, the vehicle isn't yet fully assembled.* We needed one more pigtail** to fix it (the connector was broken beyond repair). My manager grumbled that it cost $200 for that connector, which genuinely isn't my concern. It's not my fault that the customer tried to fix it himself and caused a disaster.
Mid-repair . . . did I mention the number of data lines that were cut through? That bare wire you see is the drain/ground wire for one data line (that one's audio; most of the CAN buses are twisted pairs (which you can also see in the image).
Oh, I should also mention that once I did have it running, the alternator warning light came on . . . to nobody's shock, the initial problem the customer tried to fix is still a problem. Sure you can fix it yourself. . . .
______________________________________________
*It's possible by the time I post this blog it will be, in which case there might be another section saying that it was fixed (or that after fixing the alternator and test-driving it, another problem occurred). If there isn't, either we're still waiting for parts/a bay to put it in, or it was just the alternator all along and the customer 'saved' himself an unnecessary $1200-$1500 in self-inflicted repairs.
**In automotive parlance, a pigtail is a connector with a length of wire that you can splice in; you can also get (for some applications) just the connector and put the terminals in yourself.
If I were the one selling the job, I'd have just priced out the under-dash harness. For starters, it would have come with that $200 pigtail I still need to install. Secondly, while I fixed everything I could find, there are almost certainly some wires that are partially broken inside their insulation. Thirdly, if any poor bastard in the future has to do any circuit diagnosis, good luck; depending on where they look they're gonna find lots and lots of white wires with a smattering of purple and blue and a few other colors I happened to have, and fourthly, I'm not the best solderer in the world (although I'm better now than when I started this job, lol). Oh, and fifithly, one of the data lines going to the gateway module doesn't have the correct terminal in the connector—we didn't have one, couldn't get one (apparently), and so I improvised with one that we could make fit with some minor modifications.
And let's round it out since some of our favorite beverages come in sixes:
Source
Even if we'd replaced the harness, this would still be a wild card: everything seems to work for now, but who knows how damaged the various modules got by getting voltage (or ground) on a wire that wasn't ever supposed to have that? The fact that pushing the hazard flasher button engaged the starter tells me as the failure progressed, wires crossed that never should have.
I suppose time will tell on that last one. Smart move by the customer would be to trade it in as soon as we fix the alternator and give it back; let it be someone else's problem in the future.
Friday before New Year's, my manager said that we really needed the bay that the Explorer was in, and I informed him that even if I worked on it all day on Tuesday, it still wouldn't be done. My prediction was accurate; however, late Tuesday it was done enough that it could be backed out.
Also worth mention, he never once bothered to look at it before I was way deep in the repairs; I think he might have opted to get the whole harness if he had.
Outro!
I did so much soldering I wore out one soldering iron and had to buy a new one over the weekend! Ask me for soldering iron recommendations, I've got one not recommended and one highly recommended option!
derpicdn.net/img/view/2023/4/6/3094659.png
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Damn! I'm honestly impressed the owner managed to drive it there in the first place. And yet, the only thing the customer thought was wrong was the alternator? They're lucky the damage wasn't worse.
Also worth mention, he never once bothered to look at it before I was way deep in the repairs; I think he might have opted to get the whole harness if he had.
i was thinking the same thing.
but you do get pied by the hour,
5763318
Oh, he didn't drive it, it got towed in.
Damage was about $1500 and it would have been way more if my manager had gone full boat with the labor (which I think he should have, but that's just like my opinion, man). Mind you, that $1500 doesn't include repairing what was actually wrong with the vehicle, which will be the subject of another blog post to be posted SoonTM.
5763320
Dude, when I first voted you could make a down payment on a house for $1500.
Baby Bòmer
5763313
I... wasn't aware you could "wear out" a soldering iron.
Nice. For Christmas I got to buy a new mirror for my vehicle. For New Year's, a new born.
... I would have rather broken my fingers again.
A couple of those wiring pictures actually made me wince.
Damn. I’m a noob when it comes to how cars actually work, and yet some of what he did and those photos was tough to look at.
Yeah, dude, of course you can fix it yourself, that’s why we have mechanics and garages who make a living out of doing work anyone can do themselves! Yup, that’s totally how it works!
Yes Veronica, thats how bad the insides of you nice new shiny car actually look.
Before you crashed it.
Exposed wiring is best wiring.
Edit: What's the point where it's just worth it to get a new wiring harness and use that?
Sometimes you just wish you had wings to fly you know?
I wonder what they thought when they saw the bill? I hope they learned their lesson because all that electric work on new vehicles is a pain in the rear.
5763313
Do tell!
I am familiar with aftermarket remote starters; my grandmother had one installed in her Ford Windstar. This familiarity is why I will never get one for my own vehicle. It worked fine for a few months, but soon started to glitch. It got to the point where it could only start with the remote start. Some time after that, the glitch progressed to the point where both the remote start AND turning the key were needed to start it.
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Okay, so maybe wore out was being too vague . . .
I have a Snap-On butane soldering iron, which has some really cool features. It's got a magnet built in, so you can just stick it to the car or the hoist or whatever, and instead of having to use little wrenches or hex keys or whatever to change the tips, they just twist on and off with a knurled plastic bit . . . and that's the problem with it. The pizeo ignitor is in the tip, and they cheaped out by using a bare wire that's hardly long enough in the knurled plastic bit, so the ignitor doesn't always work. At first, it was reliable, then it got less and less reliable. The driver warrantied the tips and the new ones were vaguely better, but not really. So when I started working on this thing, I had a soldering iron that would light itself about half the time, and the other half the time I'd have to use a little wrench to disassemble the twisty end of the iron, light the butane with a Bic, and then reassemble it while it was on fire. Not ideal.
So over the weekend I ordered a Dremel butane soldering iron, and not only was it cheaper than the Snap-On, it has tips that you have to change with a little wrench but that also means that the pizeo ignitor is hard-wired into it, and so far it's worked nearly every time (and the few times it didn't, I'd just click it again and I was off to the races). It's not quite as compact as the Snap-On one, and it doesn't have a magnet, but on the other hand it's super reliable and it's under $40 (USD) on Amazon! If you're doing lots of soldering and need a butane soldering iron, this might be the unit for you.
I'll include a link to what I got. It's not a sponsored link or anything like that, I don't get kickback if you buy one
Dremel Butane Soldering Iron
5763319
It's funny, I spent so many years as a flat rate tech I still get frustrated when the labor time on a job is undersold, but it makes no difference in my paycheck. The manager can sell an engine replacement for a tenth of an hour labor, and I'll get paid for however long it actually takes me.
Middle of last year I started to slow down some on a few jobs, ones I'd rushed in the past but where I could take a few extra steps and do a better quality repair.
5763334
Yeah, times have changed. Right now I can't find a car that runs for under $1000 any more, and it's frustrating; for the longest time I managed to keep the average purchase price of a car under $200, but I just can't do that any more.
Doesn't help that right now the market's good if you're a seller; I need a new van and everybody's asking way too much. If I want a van with catastrophic rust and 200,000 miles on it (320,000 km), I've already got one, and I paid less when it only had 120k (193k km) and no catastrophic rust).
5763340
A newborn human child?
Oh dear.
I broke one finger once and it wasn't great. Well, it was more than broken, but they were able to save some of the bone . . . and shortly after was when I learned that I didn't know how to use a fork with my other hand.
5763360
As well they should have. Hopefully the wincing wasn't due to my mediocre soldering skills or the poor quality heat-shrink we have.
This was one of those vehicle where the more I looked the worse of a disaster it was. I'd take a mouse any time; they usually only chew a half dozen wires at most before they move on to something else.
In hindsight, I'm kind of impressed it ran at all with so much wrong with it. There's some really good failure management built into Ford's computer system.
5763363
It was an impressive disaster!
What most surprised me was that when I got all the wires fixed and the vehicle put back together enough to test it, everything actually worked. All those wires and I got it right on the first try!
Well, everything except the alternator, and that's why there's gonna be a part 2 to this blog
Years ago when my house needed a new roof and I paid a guy who knew what he was doing to put a new roof on, some people asked me why I didn't do it myself. It's because as a professional tradesman, I know what I don't know. I could probably figure out how to shingle a roof, I might recognize some of the issues under the shingles, I might be able to watch some YouTube videos to learn how to put in flashing around my power pipe or the sewer vents or what have you, and I'd spend all summer working on it and maybe get it right, or maybe fall off . . . or I could pay someone who knows what they're doing, have it done in a few days, and have confidence that it was fixed right and wouldn't give me any problems for decades.
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There's lots of fun stuff to be discovered under trim panels in cars. The automakers hide all the parts that make it go under smooth plastic with chrome accents, but I know what's really going on under there
5763370
Agreed. Put it out there where I can see it and find problems that way, rather than being hidden away behind a steel brace (and under the steering column and instrument cluster)
This was very much the point where it was worth it.
The drawbacks are that that harness is probably expensive (I'd guess a thousand dollars), and the whole dash has to be pulled to replace it.
The plus side is that it's faster, you aren't dealing with some likely questionable solder joints (or spots where the wire is partially broken inside the insulation that I just didn't see and are fine for now but will give trouble down the road), and if he'd gone full boat on the labor (as I think he should have) it would have been cheaper, since it's less time to pull the dash than it was to solder all those wires.
I did have to do multiple wiring harnesses on a vehicle once after a fire, and I'm honestly surprised that the insurance company didn't total the truck--on that one, I had to strip out the dash and interior, as well as the top half of the engine just to get access to the complete wiring harnesses we were replacing.
5763378
Yeah, tell me about it
5763392
Hopefully that 'fixing' it himself didn't save any money versus taking it to the professional.
I hope so, too. Some people don't learn, and others take their painful lesson and apply it later in their life when other, similar situations arise.
Like, in terms of diagnosing the problem the guy was wrong (we'll get to that in the next blog post), but if he'd known enough to at least zip tie the loose wiring harness away from the steering shaft, he wouldn't have been out anything extra financially.
5763410
There are some good ones out there, and even some of the mediocre ones out there are okay so long as they're installed correctly and with skill (which is rarely done).
I think I've got at least one other mechanic blog where the aftermarket remote starter was the source of the problem; that one had been installed by stripping portions of the wires bare, twisting the remote starter wires around them, wrapping that connection with electrical tape, and hoping for the best. Repeat thirty or forty times, and . . . well, you can imagine.
A lot of times when we have issues that might be the remote starter, we'll often remove it first and then see what we get, especially since on most modern vehicles it has to be tied into multiple computers and it has to spoof the security system on the car. I can only think of one case where I found a vehicle that had a problem that could have been the remote starter and then upon further inspection decided it probably wasn't--it was the highest-quality install I'd ever seen; someone spent a lot of time installing that unit, and if you're spending that much time you're not using the cheapest black box you can find.
5763477
Indeed
Oh i wish some aeronautical company would use my idea of adding rocket engines to some wings to help fly
Seriously CMON!
I've had a few cars that needed MAJOR electrical repairs after something went pear shaped.
1: 1989 Toyota Cressida with burnt wire harness v/o radiator.
2a: Toyota U-Haul van where the EGR modulator valve feeder hose came off it's pipe, and melted through 3 engine harness wires, thus melting a critical circuit inside the engine ECU. V-6 engine so the harness is difficult enough to access to require removing the intake plenums.
2b: One of the other techs had the same exact problem that went pear shaped enough that they simply replaced the engine harness.
3: T100 truck/Previa minivan (can't remember which [both?]) with critical wire harnesses being damaged and shorting on auto trans shift linkages/other underdash brackets/tabs (Toyota builds such parts using old razor blades).
5763470
When I was a teen, you could buy a junked car for $50 & have FUN with your friends. Drive it down the sidewalk & take out all the mailboxes & decorate hedges, put your bumper on the car ahead of you & floor it, etc.
Small town, 4 cop cars so....only ever got caught once (STILL thank God I wasn't in that car at that time & PA didn't take your fingerprints or picture when you got your DL.)
5763468
Better it than a car.
Super glue a couple magnets to the new iron and it'll be magnetic too.... bonus evil points if you order the magnets in the mail.
But it DOES sound like a good deal.
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Eeyup. A true human child. No possibility of him being anything else... Definitely.
I discovered the true extent of my ambidextrousness when I broke mine. I apparently write just as poorly with either hand, but I can operate power equipment just as well, if a tad bit slower. The long range automatic hole puncher was a tad bit difficult to operate.
Wow. I feel better about the JCB loaders I need to work on today. One, the fuel cap got left off for an unknown amount of time. So feed got into the diesel tank, and sucked against the intake. In Michigan last week.
At least, I'm certain that's why there is no fuel being pulled in, after changing the filter and trying to prime it.
The other one is more wiring related, I suspect. Four wheel steering is great, until the front and back wheels are out of sync and the machine can't detect when the rear wheels are square. So it goes a bit sideways. On the plus side, I need a platform to work on the shop furnace and that loader works OK otherwise...
Related to DIY, I once tried to install an aftermarket radio in an '01 Sunfire. That was a disaster that kept taking out the tail lights and dash lights. Fortunately I was able to revert it with no problem. That car also had the transmission wire harness damaged by an idiot at a quick oil change place who was wrenching on the oil filter hard enough to rock the car.
I did my own oil changes after that $200 plus repair.
Thanks for the soldering iron recommendation! Battery powered just doesn't seem to cut it, and I'd rather not use my nice bench top one in the farm shop.
I've been curious about Tesla's 48V Power over Ethernet system and how it cuts down on the wiring harness complexity. Have you ever compared notes with a Tesla mechanic?
5763482
It's been done before with JATO, and there are some people experimenting with electrical propellers (or jet engines, I don't know for sure) to get the same effect. I'm very much not an aeronautical engineer, so I don't know how practical those ideas are.
5763483
I've had to pull off intakes (or other engine components) to access wiring before, and I might have to do it again on a Wrangler if the customer authorizes diagnostics. The harness that's affected (we think) runs under the intake; we don't know what's wrong with it yet, but we do know it blew a 25A fuse while driving.
That's the smart way to do it if you can get one.
I mostly missed the glory days of the Japanese car companies having ungodly sharp brackets, but I got to experience it on Hyundais. Chrysler also made intake gaskets on one platform (the 3.3/3.8) that were essentially razor blades, and you had to pull them off the RTV to get them off the block; I'm sure I've got scars from those stupid things.
5765401
Oh cool
5763490
I was around for the tail end of those days; one of my friends bought a Jeep Cherokee for under $100 and with under a hundred in repairs had a fun dune truck. Lasted longer than you'd have expected; it was still drivable when he sold it. Not on the road, but okay for trails.
I never did anything that crazy, for better or worse.
5763509
Yeah, that's not an unsolvable problem if I do want it to be magnetic. So far, the fact that the ignition trigger also serves as a prop has been good enough for my purposes.
I've used it considerably more since that Explorer, and it's held up nicely. Can't really speak to the long-term yet, but it's a good price and it does what it says on the tin, so. . . .
5763612
Congrats!
Yeah, that's been my experience, too. I can write with both hands, although not as quick with my left (ironically, more legibly, 'cause I have to spend more time making my letters). And as I'm sure you've also learned, working on machines means you've got to be able to get whichever hand you can into the tight space where the broken component is, so you've got no choice but to learn to operate tools with both hands.
5764681
Of all the things I've cleaned out of fuel systems, feed isn't one of them. Air filter boxes, yes. Mice love stockpiling stuff there.
As long as you're only operating at slower speeds, crabwalking can be a feature.
I can see messing up the wiring with the radio, I've seen plenty of questionable installs in my day. I personally wouldn't put in a radio without the adapter harness, 'cause that way if I want to revert--or if the radio causes unexpected problems--I can just unplug it and start over.
Also unrelated I once changed the radio in an Astro van while I was driving it on a boring state highway. Er, I mean a closed circuit course.
Not sure how someone would manage to damage the transmission harness changing the oil filter, but knowing where it was on those cars (which I don't miss working on), I can kind of see it.
Let me know how it works for you! So far it's been great for everything I've needed it for. The only downside is if you're not paying attention the the flame outlet hole and point it towards something you don't want to melt, like your hand.
5764747
I don't know much about them, but from what I've heard it's a terrible idea. Yeah, it cuts down on complexity and the number of wires you need, but you've got too many functions controlled by the same wires; if something goes wrong you loose too much. I would guess that even with all the catastrophic damage this Ford had, if it had crashed on the way here it would have still set off what airbags it could, for example. And I've seen plenty of other vehicles with shorted circuits that have caused one system to fail but others still work, or badly-damaged electrical systems still managing some modicum of control I can't see that happening with a heavily-networked system; you take out one thing you've lost everything.
Maybe I'm being unfair to them since I don't know how they wire their stuff, but my years of experience in the field tells me it's a bad idea.