Mechanic: Massive Network Failure on a Town and Country · 2:11am May 3rd, 2022
Oh boy, this was a fun one. And belated; this was at the beginning of October last year.
Anyway, get your favorite drink, we’re going on a wild ride!
The vehicle in question was a 2013-ish Chrysler Town & Country, with all the standard options. Pushbutton start, power sliding doors and power liftgate, Chrysler’s 3.6L motor, and it won’t start. It got towed in.
I grab the key fob and try to unlock it, but the vehicle doesn’t respond. Now, I’ll admit that I have a low opinion of our customers sometimes, but I would think that they would say the battery was dead and would have tried to jump start it if they suspected it was dead. Could be the wrecker driver left the hazards on and that’s what killed the battery, who knows?
Potentially, getting into the car is a problem if the electrical systems is down, but for most cars with fobs they’ve thought of that. There’s a key concealed in the transmitter, which you can use on a door lock on the driver’s side.
[There is also almost always a provision to start the car some way if the battery in the transmitter is bad . . . we’ll be getting to that.]
The key works with a bit of jiggling; this lock has probably never been used since the vehicle was new. Opening the door also demonstrated that the battery was not at fault; the content alarm immediately went off, sounding the horn and flashing the parking lights.
I tried to use the pushbutton to wake the vehicle up (that would stop the alarm), but no joy. Then I held the fob right next to the pushbutton which also didn’t work (in many cases, there’s an antenna that can pick up a dead fob in the pushbutton; in other cases there’s a different method used).
Since the alarm is annoying, my next step is to open the hood and pull the fuse for the horn. The alarm’s still going off, of course, but now you can’t hear it.
And now it’s time for some research. The fob doesn’t work, so how do I turn on the vehicle?
Chrysler, in their brilliance cheapness just installed the pushbutton over the keyslot, and all you do to start the thing with a dead fob is pull out the pushbutton and then put in the key like it was a van that wasn’t pushbutton start. That should allow the antenna to read the key, and then you’re good to go.
That’s the theory, at least. In this case, the vehicle still won’t power up, and this is now a challenge.
Normally, when you have some sort of network failure, you scan codes in all the modules and see what’s working and what isn’t working. If, for examples, all the modules on the network say that they’ve lost communication to the radio, and I can’t communicate with the radio, it’s a fair bet that there’s something wrong with the radio or the network wires to the radio.
But when you can’t even power the vehicle up, that means you can’t communicate with anybody. All the modules are asleep, and whatever codes they may or may not have are unrevealed.
Vehicles turn off nearly all their modules shortly after they’re shut down to save on battery. Obviously, something needs to stay awake so that when you come up to the car with the remote and push the button the car replies. Back in the day when cars didn’t have as many modules, that was often the body control module; now that there are more functions that the vehicle has it’s sometimes a dedicated module . . . on this particular vehicle, it’s called the WCM module (which if I remember correctly, is the Wireless Control Module). That one ‘sees’ the wireless signals (the remote) and then tells the other modules what to do.
At a guess, although I didn’t find documentation on this particular vehicle, the content theft module (called the PEM--Passive Entry Module) stays awake enough to know if the doors are opened.
The WCM module serves a second function on this vehicle, too. It’s where the key or the pushbutton goes, and it doesn’t recognize the key or the button being pushed.
Now I have a problem.
My first suspicion is that the WCM has gone bad. It cannot receive any inputs from the key, or it does and then fails to act on them. As a result, the PEM doesn’t know that a key has been used to open the doors, or that the ‘unlock’ button on the key has been pushed, and it does what it’s supposed to.
Furthermore, none of the modules will wake up since the WCM doesn’t tell them to. This also means that even if I can figure out some way to communicate with modules, they probably won’t tell me that the WCM is bad, since they wouldn’t know. It didn’t tell them to turn on, so they didn’t.
Even if I’m reasonably certain which module has failed, I hate throwing modules at things to see if that fixes it. Especially an expensive module, especially a security module, and especially on a Chrysler. First, since it’s a security module, you got to jump through extra hoops to program it . . . if it was easy, that would be a great way to steal vehicles.
Second, this is a network that was designed as a collab between Chrysler and Daimler (who used to own Chrysler) and updated by Fiat (who now owns Chrysler). There’s probably still some legacy Mitsubishi stuff and Renault stuff in the design, too. I can’t remember if I ever blogged about the dead Dakota, but our specialist needed to use three different factory-level scan tools to program it, one of which was communicating with a legacy server in Europe.
Point is, I’m going to rule out everything that isn’t the WCM before I say it needs a WCM.
Armed with wiring diagrams, I managed to figure out a way to use test relays to power up some of the electrical systems on the van even without a key, and I’m finally able to communicate with some of it.
On the one hand, this isn’t the greatest solution, and I can’t make too many assumptions with the vast number of communications codes it sets. After all, I’m only partially powering this thing up, and some of the modules in question aren’t fully powered-up. The PCM, for example, has I think five different power inputs to run all its functions, and I can only be sure that two of them are live.
On the other hand, I’ve got some functionality on the network that the WCM module is on, and this is actually quite useful. I now know that some module failure isn’t taking down the whole network (this can happen, something can fail in such a way it sends gibberish down the network so that nobody else can communicate). Furthermore, depending on how things are connected to each other, I might be able to rule out a wiring fault: high-speed networks are usually arranged in a line with a specific module on each end, and the communication wires pass through the module and on to the next one. If, hypothetically, the WCM module is somewhere in the middle of this, and if I can communicate with modules on either side of it, I know the wiring’s good.
Here’s where it starts to get weird.
On the high-speed network, I can communicate with the PCM, sometimes the ABS, and the airbag modules kinda come and go. Also, interestingly, while most of the low-speed network has issues (as it should, since the vehicle is only partially powered up) the Liftgate Control Module is happy as a clam and working as intended.
It looks like I can see on both sides of the WCM, but the way that the topography is laid out on the computer, I can’t be certain. It might be spliced off on its own little branch--I don’t think it is, but I can’t say for absolute certain.
My manager decides that it needs the WCM, just based on its symptoms and its refusal to recognize the key. I’m not entirely convinced, but I don’t have any better ideas.
To replace this, you’re supposed to pull the upper dash trim, but he says when he worked at a Chrysler dealer back in the day, figured out how to get them out without doing all that. There’s a trim panel you can take off to get at the bolts, and then . . . well, he doesn’t quite remember that next part, but it’s doable.
Since y’all probably don’t know what all that entails, here’s a picture of a Town and Country with the upper dash trim removed.
While I’d love to say he had to admit he was wrong, you can get it out without pulling the upper dash trim. It’s a fun topography problem, unplugging the wires is difficult, but it’s doable and you only have to pull out a couple fasteners and panels and kinda pull the lower dash trim out of the way.
Plugged the new one in, went through all the different hoops to get it programed, and when it was, not only did the vehicle not start, it was in fact worse than it had been before. Now the entire network was down; even with my clever little bypass nobody would talk.
Well, not quite nobody; the Liftgate Control Module was still online. There are twenty-six networked modules on the vehicle, and now with the new WCM, only one of them is still active. If I plug the old WCM in, I get everything I had before back.
The first, most obvious guess is that we got a wrong part from Chrysler. Shouldn’t happen, but it could have. Or else the programming went wrong somehow. So I pull it back out and check the part number, it’s the same as the part number on the box which is also the same as the part number we ordered, and it’s similar to the one I took out (I think it was a different revision number but otherwise identical).
Also, now that I’m pondering why a new part made the network situation worse rather than better (which would be ideal) or at least exactly the same, and I’m also kind of going back through my notes and realize that I could not communicate with the PEM. That’s the Passive Entry Module, in case you don’t remember. The one who beeps the horn and flashes the lights if it thinks you’re breaking in.
Not only can I not talk to it, but the Chrysler tool, which has a fantastic color-coded network topography on it, also shows the PEM as being offline. But it can’t be offline, it’s activating the alarm, and it has to be doing that somehow.
I’d had my suspicions about it before, but hadn’t done anything with it. I was going to unplug it, just in case it had gone rogue.
It lives down at the passenger side of the dash, tucked up against the fender. I couldn’t see it, but I could feel it. Couldn’t get to the wires, but I thought if I took the glove box out, I probably could, so I did that. Glove box comes out easy.
And the answer to the problems was literally staring me right in the face.
No, it wasn’t the PEM being partially-melted, or a toggle switch labeled ‘network on/off’; instead it was a single length of mouse-chewed wire hanging down. A single light blue wire, but where there’s one wire a mouse chewed there’s normally more.
I stuck my phone into the glove box hole and too a picture up towards the wiring harness, and there were more chewed wires, and this is the harness that (among other things) goes to the PEM.
Since I was there, I unplugged the PEM just to see what would happen, and to nobody’s surprise nothing changed.
Then I pulled all the upper dash trim off to see just what I was dealing with, and repaired all the gnawed wires. Some of them were network wires.
Once they were fixed, the vehicle started and ran with the old WCM, the key fob worked, and everything was good again.
Sometimes automakers like to keep secrets.
Especially when it comes to security. That information gets out, of course, but it’s not always easy to get. I don’t think I ever found a wiring diagram for the PEM, nor a complete breakdown of its functionality, although I sure would have looked if I thought it was the bad module.
Here’s what I think, though. I think that both the WCM and the TIPM are always awake. The WCM is waiting for wireless signals to come its way, and the TIPM is in charge of all the vehicle’s power.
I think that when I would hit buttons on the remote, the WCM would see them. Remotes send out a 315 or 433MHz signal with a code and if that code matches the one that the vehicle’s security system knows, it will do what you told it to. If the code does not, the vehicle does nothing.
So the WCM just got a code 24609 (let’s say) and a request to unlock the doors, what does it do with that? I bet what it does with that is ask the PEM if that’s an appropriate code.
And the PEM, who has had its wires sabotaged by a mouse, says nothing, so the van does nothing.
When I open the doors, the TIPM does not see a message from the PEM saying that things are okay, so it decides to set off the alarm. No status message, alarm goes off.
When I stick the key into the WCM, it asks the PEM, ‘is this my key?’ And the PEM, of course, doesn’t answer.
So the TIPM, who hasn’t seen a valid key signal, does nothing. It powers nothing up. For all it knows, you stuck a fork in the slot.
Which leads to the final question: why did the entire network fail when I put the new WCM in? (Well, except for the Liftgate Control Module which I guess doesn’t care what else happens on the van.)
I’m guessing that part of the programming process is telling the PEM and/or the TIPM a secret code that the WCM has in it, once again for security purposes. So if you push the button or turn the key, it says, ‘hey this is WCM 171-467A, and I have key number 24609, is that okay?’ Obviously, with the PEM being off the network, it never would have known that a new WCM got installed and programmed and that security code mismatch/lack of code might have caused the TIPM to shut everything down since, as far as it’s concerned, this is a blatant theft attempt.
I suppose if there’s a lesson to be learned in all of this, it’s that you can save a lot of time on diagnosis by understanding who communicates when to what and over which network.
Also, I guess, if my manager hadn’t suggested a shortcut to remove the WCM, I would have found the wiring problem before attempting to install or program the new one.
Also, in case you’re curious, here’s what the network topology screen looks like on the Chrysler scan tool:
Blue modules have no codes; yellow modules have codes. Grey modules are not equipped on the vehicle in question (for instance, this one lacks a standalone TCM [it’s built into the PCM]), and modules which the vehicle has but which aren’t communicating are red. I wish I’d taken a picture of the screen with every module but the PLGM in red. Best I’ve got is one where some of the network has failed, and most of the modules which will communicate are mad:
(this is never what you want to see)
In other news, we supposedly have a new guy starting soon. He dropped off his toolbox today, but couldn’t stay to work, I guess. We’ll see how he does.
Yay new guy!
I was betting on that bastard communication bus junction block thing. Though I think that might only be on later models. It's a little box that sits above the glove box and is the main connecting point for all the network data lines. Which is completely idiotic, since every other car just has wires spliced or crimped together. The plugs are not water proofed, and the data lines obviously work on such low current, that even a tiny oxidization layer on the terminals causes all sorts of weird communications errors. Unplug and replug, maybe spray with contact cleaner if you're feeling generous, and good as new. I've already had two of those...
I owned a Chrysler. ONCE.
I vowed that I would never own another unless I won the lottery.
Then, I would buy a duplicate, run it through a car crusher, have it encased in a block of clear lucite, and put a plaque on one end
MY OTHER CAR IS A
ROLLS ROYCE
It would be a coffee table, or an end table (depending on size).
Are you quite sure that you did not leave out the step where you sacrifice a white, or is it black? chicken in the light of a full moon before you start work on one of these modern cars?
Had any old timer tell you about setting the points on a car with the cover from a book of matches?
It works I've done it.
And this is why I will GLADLY stick with a Ford (preferably an F-150)
I've never had the pleasure of owning a Chrysler, but I've heard a laundry list of stories! While reception is a bit mixed, the best car I've owned is still my 2001 Saturn SL1. Originally my mom's car, then sold to me, It lasted 20 years and never had any problems other than a couple of flat tires.
It finally died in early 2021 when the transmission shat itself in the middle of I-215 when I was literally driving home from passing my CDL test. It completely ruined my victory lap. (I even had Dunkin Donuts on the passenger seat to celebrate with!) It was so sad to see a car I pretty much grew up in get towed away for the last time.
"Well, not quite nobody; the Liftgate Control Module was still online. "
Sir, the bad news is your van is broken really bad. The good news is the liftgate works so you can use it as a storage unit while you go out and buy a Toyota.
At first I was guessing the fob got fried. Finding out that there's a key slot behind the push button is neat though, do you need tools to pop the button off or is it just a fingernail away?
This was actually very interesting. When my fob started going it was interesting to see the backup systems for the car just in case. My backup fob antenna is in the cupholder
could say you found a "backdoor" into the system
5654930 I just burn incense and chant prayers to the machine spirit.
5654940 I have a 93 (currently switching to a 92) Chrysler Lebaron. Definitely one of the best cars I've ever owned. It's a much older breed of Mopar, though. Still clinging to the glorious Lee Iacocca days. They were simpler back then, yet still very modern for their time. In 1988 they had a fully electronic and computerized transmission that could adapt to your driving and tell you how worn out it was. Years ahead of their time. My car just goes and goes, repairs are simple, and it's fun because it's a convertible.
The original Saturns were good too. I've had a few of those pass through my hands. Never really owned one. But worked on many. They never had any real problems. Simple, easy to work on. Good old A to B cars. Then GM stepped in and started making them more GM, and therefore less good. Shame. Also their transmissions were very strange. Basically a ripoff of Honda, which themselves have one of the weirdest transmissions... an amalgam of a manual and a typical automatic. That's why they whine in reverse, just like Hondas, and just like a manual transmission... because it basically is. They're complicated and somewhat delicate. Not sure what Saturn engineers were thinking.
All that, and people wonder why I prefer my old truck. I'm not exactly old yet, but I've been seeing a lot of strange stuff these days and it makes me even more concerned for cars now. For example, the new Ford Explorer headlights? They're data driven now, so it's just power and communications wires, and tbey do weird things when unplugged and plugged back in. Escapes have modules in the doors, and if something goes wrong there, you lose the entire door, or it does strange things as well.
I like my old '95 Ram...technically 3 computers, but that's it. Engine, transmission, and the single air bag module.
Oh no, not just a town but an entire country as well has lost its network!
You want electrical problems? Lately, I've been getting into YouTube compilation videos of mechanics showing some of the most interesting mechanical failures they've seen. I think the one that sticks out the most to me was when the mechanic inserted the key, turned it, and the engine started up. The strange thing was that it wasn't the ignition he'd inserted the key into; it was the door lock.
Also, you don't want mice anywhere near electric wires.
I kinda wanna see someone hook up a bus thief to a car's internal network, reverse-engineer the authentication traffic between the modules that control whether or not the car will start, and see just how ridiculously bad their internal security system probably is because they think they can just keep it safe by keeping the schematics and specs a secret.
If you have to rely on security through obscurity... you're not secure at all.
I hate dongles or fobs or whatever, but whenever I use the actual key to unlock, the alarm goes off anyway, so I guess OEMs are trying to move away and actually abolish actual keys.
What happened to the former new guy?
5654930
Is that like using a folded-over piece of paper to set the gap between the magneto and flywheel on a Briggs and Stratton Sprint engine?
5655499
sounds like it
5655012
Please find that one and share it with us
5655042
About 12 years ago or so I sold my uncle my old truck - a 1991 Dodge Dakota. A few years after that it would start. Towed it to the mechanic and mice had chewed the engine harness to bits. It was too old to get a replacement so the mechanic pretty much had to rebuild the whole thing splicing in new wires.
He still has it tho it doesn't get much use. I drove it a few years ago and it REALLY needs some work on the steering. Scary sloppy! I kinda miss that truck - nice size, long bed, not too big. I hate how even "small" trucks today seem like hulking behemoths.
5654925
So far he’s getting some of the fun heavy jobs I don’t want to do. Like putting an oil pump on a newish 4.3 (the timing chain driven one) and an engine in a Ford Expedition.
So far the only failure of one of those I’ve seen on a Dodge was on a brand-new wiring harness. Had to fix a Ram that had a small underhood fire, largely focused on the battery and fuse box. Something, I can’t remember what, didn’t work when it was all wired back up, and that was because Chrysler plugged stuff into that stupid junction block wrong.
5654927
I’ll be honest, while I’m not much of a Chrysler fan, they’re pretty good at building minivans.
5654930
Yes, and I’ve seen it done. Rarely, we don’t get cars with points at the shop.
5654933
If/when I have a Ford F150 blog post, you might want to skip it . . . we’ve got a lot of customers who have them, and some of them have weird problems.
5654940
Those were great cars. Simple and reliable, really good fuel economy.
That is unfortunate. I kinda felt the same when my dad’s Chevette that I sort of grew up in got wrecked. I wasn’t in it when that happened, which is probably for the best.
5654944
It’s even funnier to me, since some GM products that have a liftgate control module (LGM on GMs) are super unreliable. Like on Trailblazers, you can watch the LGM data live, and see it switch between ‘ok’ and ‘not ok’.
5654956
That was my first thought, too.
The vans are the only ones I know of that do it that way, although other products might. You just need something you can slip behind the button, it’s a friction fit. A little screwdriver does the trick; even a butter knife would probably do it.
5654978
I think that all cars that have pushbutton have some way to start the car if the Fob’s dead. A lot of them, you can hold the key by the button (since there’s an antenna there), but not all of them. I know of keyslots in the center console or the glove box, and there might be other places. When you program keys in at least some Fords, the key has to be in the slot to be programmed.
5654980
5654982
Maybe I should try that. I typically just yell at them.
The 1.9L engines were known for burning oil, but as long as you kept putting it in, they were fine. Other than that, there weren’t many problems that I know of, either, just normal maintenance stuff.
I’m currently diagnosing a Caravan six-speed, and it apparently has two fourth gears because . . . reasons? I need to find a reason to go through the theory and operation more, to see if I can figure out why it’s got two fourth gears.
5654984
It’s an interesting world, and there are lots of reasons for why the automakers do the things that they do (part of the reason is to cut down on wiring wherever possible). There’s a lot of stuff that’s mandated by the feds for safety or emissions, and a lot of stuff that people just want. Like a good-sounding radio, power windows that go up and down automatically, etc. I do also miss the days of really simple cars, since there wasn’t much to break, but they also really lacked in creature comforts.
I’ve got a similar one, a 98 (I think) Ram. It might have four computers; I can’t remember if it’s got ABS or not.
5654987
I know, right? A complete disaster.
5655012
There’s a bunch of videos like that, and I’ve seen a few of them as well. Some of the problems that appear in those videos, I’ve seen (especially ones related to rust, or ones related to people driving their car until it won’t drive anymore). Not that long ago we had a G6 that would turn itself left or right and you had to fight it to get it to go the other way. That was an installation/programming error on my part, but it was an interesting failure.
5655042
You very much don’t. They give us a fair bit of work, but it’s not work any of us enjoy.
5655061
It’s not exactly security through obscurity, although that’s part of it. Making the information not readily available helps (such as knowing which module tells which module what for security purposes), but that’s not the only way they secure cars. A lot of times, the security system has timers built in; for example, today I worked on a car with a locked-out radio. It would give you three attempts to enter the correct PIN, then the radio locked itself for a half hour before you could try again (and the car had to be on for that half hour timer to count). Given the number of potential combinations (1.6, four digits), you could brute force it in a few hundred hours if you wanted to. Most smash and grab thieves wouldn’t want to. [Unlocking the security system the normal way also has a countdown timer on some GM and Ford models, usually a half hour.]
In one of our classes on pushbutton start, the trainer had hooked a scope up to the data wires, so we could see the signal of the appropriate module querying the key for its code. It tried three times, and when it didn’t get a response, gave up.
A lot of cars use rolling codes, I don’t know exactly how they work but they make it harder to clone a key. A lot of sophisticated auto theft rings know how to clone wireless keys just the same, and can get the information off yours by driving by your house, then coming back later to steal the car with a new fob they made.
5655208
Actual keys are kind of a pain for the automakers. Locks are probably more complicated and expensive than wires, and not as flexible (as to where they’re installed) as a keyswitch.
5655339
I’d have to look back to find out when the last time we hired a new guy was and then figure out which one it was. In a nutshell, most of them quit for one reason or another. Sometimes after only a few weeks.
5655517 5655499
Probably more or less the same idea. A small gap a certain number of thousandths, about the width of a matchbook cover.
Some cam sensors actually came with a little paper stuck on them to set the gap; you push it down until it touches, and the sticker makes sure it’s got the right gap once the engine’s started.
5655527
Nowdays if it’s popular enough, you can get them online . . . we had to get one for a 90s Wrangler that had its engine harness eaten by mice. Found an online salvage yard that specialized in Jeep wiring. Mostly those harnesses have to be fixed by some unfortunate mechanic. I’ve done a few, and not liked any of them.
Yikes!
That annoys me, too. I had a couple of 80s S-10s that were the perfect size. Small enough to get good gas mileage, big enough beds to haul a reasonable amount of stuff.
The first gen Canyons and Colorados were about the same size as a S-10, but they’re horribly engineered and ugly and I hate them.
5655861
Thats the weird thing with those explorers...assuming a common ground, I'm pretty sure it would actually use less wires per unit if it was analog controlled rather than how it is. Would likely have fewer weird things going on with it, too, when you have to unplug them to upfit it as a cop car. What really sucks about data driven lights, at least in that regard, is you're stuck with the alternating headlight pattern that Ford puts in the BCM, or whatever computer runs them.
Also, I think the 98 Rams did have ABS. Mine has the light in the dash for it, but was never equipped. I'm not sure what their thinking was there.
5655870
See, I love jeeps but I'd never buy one. I've heard too many horror stories on how much repairs costs for them over the years.
5655860 Not really sure what you mean by two fourth gears. But bear in mind the 6 speed is mostly just the A604 with two extra gears added onto the end of it. Much like the old rear wheel drive TorqueFlites got a an overdrive gear quite literally bolted onto the back of an old 3 speed.
5655865
I'd just hook it up to a computer and let the computer spend a few hundred hours unlocking it for me while I write pony fic, but I'm not a car stereo nabber, nor do I think most of them have computer science degrees or pony fiction writing hobbies
...Why is it called the content alarm? It doesn't sound like the vehicle is very content with its situation.
...So, I'm just getting down to the point where you're talking about the layers of IT designed by different companies here, and I have to say, it's really bringing all-non-electric diesel engines to mind. Alternator-rectifier and (deep-cycle) battery? They power the lights, the radio, and some block heaters for cold weather starting. Want to start the car? Reach down, undo the lock on the starting lever, and pull to open the valve between the reservoir and the air starter.
Hm. Might want an electric clutch for the air compressor...
...And given how much of my time today I spent designing systems for a circa 1900 rail tunnel under the Straits of Mackinac, and how behind schedule I am, and what time it is, and how many blog posts I still have to get through, I should really cut the design speculation off there.
...Anyway, yes! Interesting hearing about how packed with computers modern automobiles are!
Thanks for writing, and good luck with the new guy!
5655865
Did I ever post this?
Hackers remotely start, unlock Honda Civics with $300 tech: Any models made between 2016 and 2020 can have key fob codes sniffed and re-transmitted
My favourite "You really don't understand the principle of using a physical access requirement to enhance security, do you, automakers?" line was this:
(For those not up on the jargon, it's basically saying that automakers are late to the party in understanding the inverse square law and that technologies that more closely resemble NFC in their use require more complicated attacks.)
...I'm always reminded of the story of the laundry detergent company where the marketing department didn't understand that it's impossible to make a chemical which can selectively dissolve only lint prills.
5655866
I wouldn't mind so much if they'd stick to something that requires a physical connection. Feel free to turn the key into a pushbutton with a quarter-inch phono plug on the back or something like that... just keep wireless communication out of starting the car.
5655895
Probably meant to protect the contents of the passenger cabin from being stolen.
5655943
Oh, as opposed to a different alarm for an attempt to steal the car itself? Hm. Maybe? Thanks for the idea, at least.
5655875
Well, assuming you’ve got four bulbs (high/low, front turn/marker, sidemarker) you’re running five or six wires in there with a common ground, whereas you could do it with four in the traditional way. If you want some extra functionality, you might need extra wires, too. Some new Ford trucks have a load (weight) indicator built into the taillights.
Ford’s really sensitive about that; when one of your products kills several parade-goers because a police upfitter taps into the wrong harness and inadvertently disables the brake-to-shift interlock, so I can see why they’d do that.
A lot of times, they use one dash ‘print’ and only put lamps in if that system is equipped--for example, I’ve owned a few cars that are automatics but available with manuals which have a ‘upshift’ light on the dash, but no bulb in it. Heck, even my 70s Olds sedan has an indicator for the station wagon’s tailgate.
5655877
The idea of Jeeps is cool, especially the Wranglers. And as a second vehicle you can off-road in or drive around at your leisure, they’re fantastic. As a daily driver, they’re horrible.