YHK - yet another hacker news clone

Jailbreaking my car's navigation system just so I can change the time

181 points xx_ns 1 day ago 48 comments

gregsadetsky 1 hour ago | parent

I was just wondering the same thing for a 2013 Honda Civic - has the screen's (the "head unit"?) firmware been fully dumped and reverse engineered?

How realistic would it be to run fully custom firmware there, and even communicate over usb - for example, if I had a pi running in the car, and it used the usb connection to show things on the built-in display?

rockostrich 1 hour ago | parent

It's probably easier to just buy an aftermarket head unit. The only thing you'll need to confirm is that it supports features you care about e.g. steering wheel controls.

rithdmc 1 hour ago | parent

Probably more difficult than hijacking the display with the pi. But that's just a vibe.

EvanAnderson 39 minutes ago | parent

I'd love to pwn the head unit in my 2014 Honda CR-V just so I can stop it from sending a "Play" command every time a phone associates with the Bluetooth and the audio system was left "on".

whycome 1 hour ago | parent

Pretty awesome write up to explain their journey in it all.

I suspect a bunch of car head units will face new problems in the spring when many Canadian provinces will no longer change their clocks. The units won't get updated DST rules.

monegator 45 minutes ago | parent

which is mind boggling.

my skoda simply has an entry in the menu: DST? which puts the clock one hour ahead or behind.

This posts remind me that when i will be in the market for a new van i will have to decide to get the trafic or the vivaro, solely on the head unit they use (renault ones have had incredibly stupid design decisions for years, on ergonomics alone, even more in firmware)

iclelland 44 minutes ago | parent

That's this fall - happened a couple of days ago.

runnr_az 1 hour ago | parent

As an Arizona resident, by recent Honda CRV's clock is off by an hour for half the year. Since usually the carplay display overrides the clock, it's no big deal, but it cracks me up that, despite being a professional programmer, I have yet to figure out how to set it correctly

jerf 51 minutes ago | parent

The difficulty of setting a VCR's clock was a meme in the 1990s, and I can attest, justifiably so.

But at least it was possible. The clock setting being impossible without a proprietary and easily lost or destroyed SD card is pretty good, but we can do better. It could be just impossible to fix a wrong clock. Truly that would be the apotheosis of user unfriendly design.

220hertz 38 minutes ago | parent

I'm reminded of an old commercial depicting kids taunting another kid by asking "What time is it at Billy's house? 12 O'Clock! 12 O'Clock! 12 O'Clock!" Might have been a Blockbuster commercial? I can't remember.

Twirrim 31 minutes ago | parent

My very technical and hands on father used to have us set the VCR clock, the controls were in a tiny compartment under a flap that required either small fingers, or very careful manipulation with the point of a protractor or something.

We went from difficult to manipulate buttons through to multi-function buttons where controls get hidden through some incomprehensible maze of menu options, to now where it sometimes feels lucky if you even get an option to manually set the time at all.

bookofjoe 47 minutes ago | parent

In 1974 when I was an medical intern at Los Angeles County-University of Southern California Hospital, ALL the round analog wall clocks with hands in all 26 operating rooms were correct six months a year: there was NO provision for automatically advancing/moving them back when DST started/ended, nor did anyone do it manually.

EvanAnderson 40 minutes ago | parent

It's crazy they didn't have a centralized clock system in a facility like that. What a thing to scrimp on.

bookofjoe 9 minutes ago | parent

I'd laugh whenever I looked up and saw the wrong time....

yardie 9 minutes ago | parent

I was told by our school electrician that long ago the clocks were adjusted by the power company. So around 2am DST they would either send power at 59Hz* to fall back or 61Hz* to spring forward. This was from the era when power grids were separate and analog. With newer national grid-tie it might not even be possible to do now.

ButlerianJihad 8 minutes ago | parent

I worked in a Network Operations Center in the early 1990s, and there was a large projection display with four other monitors around it. Across the top were four round analog clocks, representing the time zones of the United States. I was one of four operators, all in our 20s.

So, Daylight Savings Time ended, and the early-morning operator had all the clocks set by the time I arrived, and the third operator came in, looked at them, and said "Great! So, did you take all four of them down and adjust the time individually?" "Yeah" "Didn't think about taking one off the end, adjusting it, and moving the others down the row?" *facepalm*

tom1337890 57 minutes ago | parent

Awesome write up. Love it. And good thing you documented it, since in half a year you'll need it again.

My takeaway: You should have just gotten the SD card and trusted the previous owner. Sometimes "simple users" do know. ^^

darknavi 49 minutes ago | parent

> And good thing you documented it, since in half a year you'll need it again.

Man this is too real for personal projects. I really need to write down my findings and thoughts more for future me.

drivers99 25 minutes ago | parent

I started using an "engineering notebook" for things like that. They are called other things in other lines of work or school (lab notebook, captain's log, ...). In an actual engineering notebook, you would use a sewn binding where you can't add or remove pages, the pages are numbered, you have an index in the front, entries are made in strictly chronological order, you'd have someone else witness and sign pages, draw a diagonal line across empty areas so you can't remove things, only cross things out with a single line, etc. All that because you might need to prove you invented something and other legal CYA reasons. Most of these requirements, you don't need for personal projects, though. But the things that are useful: keeping track of projects, what settings you've tried, what the results were, and so on. That way you don't have to reproduce it from scratch again later. "What settings did I need use to create the gerber files in kicad for manufacturing? How did I set ___ in the oscilloscope? What parts did I use to make that thing? What things did I wish I had checked last time? Where did I put those files?" You can also print things out and tape them in for reference.

warkdarrior 10 minutes ago | parent

MEMORY.md is your friend.

bgun 47 minutes ago | parent

I’m a little confused by the description of that interaction - why wouldn’t you take the SD card? Did they want to charge extra for it? Seems like even a 10 year old map (plus apparently other functionality) is something you’d want.

In any case, glad it took you on the wild goose chase that led to the write up!

mikestew 46 minutes ago | parent

That’s the part I don’t get: just take the damned card, you never know. Worst case: hey, free SD card!

xx_ns 38 minutes ago | parent

Yep. I didn't get into it in the article, but in reality the previous owner had already (accidentally) thrown the SD card in the trash, and was pretty much asking me if they want me for them to go digging through their trash to find it, and I told them not to worry about it.

bornfreddy 23 minutes ago | parent

Nice writeup. But IIUC you can change it so that it automatically updates the time every 6 months?

Barbing 21 minutes ago | parent

“No worries, I’ll hit HN’s front page instead” - much more fun!

lisper 11 minutes ago | parent

Why did the previous owner ever remove the card in the first place if they knew it broke things?

jerlam 48 minutes ago | parent

I had a luxury car from 2001 where the time could not be manually changed, only set to specific time zones. Of course, all the time zone rules had long diverged from its rule set, and it had to be changed four times a year to show the correct time.

This car also inexplicably forced you to manually choose a country, and then a time zone, despite having a GPS that already knew exactly where you were and already had chosen a previous time zone.

Carplay is nice but I would have settled for a non-luxury "clock set" button.

functionmouse 31 minutes ago | parent

Could be planned obsolescence.

bobmcnamara 19 minutes ago | parent

My 2025 Toyota has two clocks, one from Toyota, one from Android auto.

The Toyota one requires selling your driving data to insurance companies.to update the tzoffset based on location.

And so two clocks on the dashboard are off this week until I can remember where the dst adjustment is in the settings.

someguyiguess 16 minutes ago | parent

Honestly I’ll just wear a watch.

ForHackernews 45 minutes ago | parent

> The system had DRM checks which rejected SD cards without the correct CID (a unique ID burned into the card) and files with signatures based on that specific CID, so I couldn't even copy the files to a blank SD card.

FWIW, there are grey market sites that will sell you an SD burned with a custom CID so you can clone an SD card with this kind of copy protection. It sounds like in this case maybe he could've gotten away with an empty maps card + menu definitions file.

uyjulian 23 minutes ago | parent

There is code execution exploit in Samsung SD/eMMC firmware which, among other things, will allow changing the CID

RajT88 33 minutes ago | parent

Add to falsehoods programmers believe about time:

It can be changed without the SD card in the car radio.

warkdarrior 8 minutes ago | parent

The whole article is ludicrous. Why do you even need a car with an SD card slot in order to change the time? I reset all of my clocks this weekend and I don't even have a car.

ivanjermakov 4 minutes ago | parent

This question was certainly asked during a meeting 30 years ago and the answer was "don't worry about it".

somehnguy 31 minutes ago | parent

My 2014 vehicle stopped updating it's time automatically a few years ago. I think some cellular technology was phased out or perhaps the cellular contract GM had for vehicle connectivity expired.

Either way I just manually set the time twice a year now - I guess I'm thankful it still has that option.

When I was playing around with the radio in my girlfriends vehicle there was no option to set manually on the clock screen. Seems like a pretty shortsighted move to not allow that.

gopalv 17 minutes ago | parent

> the cellular contract GM had for vehicle connectivity expired

2022, I got a letter saying that my car's crash response SOS system will stop working because FCC is retiring the 3G spectrum it is using.

The car clock however is synced to the GPS instead.

If GM used NTP instead of GPS, then it makes sense that it stopped working arbitrarily around 2022.

nradov 15 minutes ago | parent

Older versions of the GM OnStar hardware used 2G cellular radios and carriers have decommissioned those networks. Adapters are available for some vehicles to use newer networks.

https://www.onstar.com/support/faq/2g-network-sunset

speedgoose 31 minutes ago | parent

The Renault Latitude is actually Samsung car right?

yowayb 31 minutes ago | parent

not quite as difficult, but reminds me of a fix I found on reddit for Subaru Outback parasitic drain: https://www.reddit.com/r/subaru/comments/1evozzf/dead_batter...

fefaOd 26 minutes ago | parent

The French auto industry... has always been "Special"

geephroh 24 minutes ago | parent

Love it! Slightly more elegant than my solution: a piece of electrical tape over the clock.

vessenes 18 minutes ago | parent

Okay, this was gratifying to read, but ... can't you wedge CarPlay onto this thing? I'd want a victory lap with root doing at least something. Bad apple on car boot, there's lots of options here!

xx_ns 13 minutes ago | parent

Yeah, I'll keep working on this to get it to do more stuff that's at least a little bit more useful, if not just a better UI that isn't 90% a useless "No maps found" screen. It's more complicated than it might initially seem because they actually have a kernel module blocking me from mounting non-signed partitions as exec, so I'll need to work around that.

I'll probably post a follow up if I get anywhere with this!

lifestyleguru 13 minutes ago | parent

8 inches or more of dashboard real estate to display "maps not found", "don't get distracted" warning, terms and conditions, and blinking "12:00". Having had rented a fair share of subcompact and compact cars in half dozen of countries, the car navigation was updated and working exactly only once.

superjan 9 minutes ago | parent

[delayed]

zodwick 8 minutes ago | parent

The revolution against shitty locked down software has begun and I LOVE IT

jdlyga 5 minutes ago | parent

I never understood why car companies don't put more effort and resources into their MMI systems. Audi is a big offender. I've never seen a more thoughtfully designed car with an MMI interface that's more frustrating and buggy.