Jailbreaking my car's navigation system just so I can change the time
- ID
- 42640
- Status
- summarized
- Published
- 03 Nov 2026, 12:29 AM
- Fetched
- 04 Nov 2026, 2:36 AM
- Provider
- Hacker News
- Category
- dev-community
- Original URL
- https://blog.nns.ee/2026/11/02/renault-hack/
- Source URL
- https://hnrss.org/best
Summary
- Score
- 4.5
- Created
- 04 Nov 2026, 2:37 AM
- Tags
- Audience
- developersvibe_coders
What happened
A 2014 Renault Latitude owner spent an hour hunting for a clock setting in the Carminat TomTom head unit before concluding the option is simply absent: the previous owner's claim that the car needs the navigation map SD card just to set the time turned out to be true, and the dash button that should open time/date settings instead pops 'No maps detected!' on every press. After a DST shift left the clock an hour off, they fetched the unit's firmware update files, found an existing (French, apparently LLM-assisted) reverse-engineering README pointing to the correct download URLs, and extracted a 'ttsystem' file that is an ext3 filesystem containing the device's root filesystem. The thread drew 306 points and 103 comments on Hacker News.
Why it matters
The concrete lesson is about artificial feature gating in embedded Linux devices: a map SD card being a hard dependency for a clock setting is a design decision, not a technical limit, and it is the kind of thing that pushes users into flashing firmware you never intended to support. If you ship embedded or appliance software, this is a live example of what a missing settings option and an unhelpful error string cost you in goodwill and support load.
Discussion angle
Would anyone here actually pull the firmware and mount the root filesystem for a clock setting, or just live with the wrong time? Worth comparing notes on which consumer devices you have already jailbroken, and where you drew the line.