As a car enthusiast diving into the intricacies of vehicle diagnostics, the recent explorations into CANBUS terminal sessions, sparked by curiosity around vehicle network security, have been incredibly insightful. Using tools like the OBDLink MX, the world of OBD2 commands and data has opened up, revealing the potential hidden within our vehicles’ systems. To further this exploration, a wired USB OBD2 ELM327 module is on the way to enable continuous monitoring of OBD2 traffic. Bluetooth modules, while convenient, have shown limitations in handling data bursts, often leading to buffer overruns. A wired connection promises uninterrupted data flow, crucial for in-depth analysis.
A key revelation during full PID scans using software like Torque was the identification of NULL PIDs – responses indicated by ‘7F’. These seemingly empty responses are actually quite telling. They highlight PIDs that were skipped during standard scans, suggesting they might contain valuable, yet unmapped, data. By analyzing a cleaned version of a full PID scan, the aim is to pinpoint these potential enhanced PIDs, essentially the ranges from Hex 0-F not initially provided. This process of elimination is a crucial step in narrowing down functional PIDs and potentially uncovering manufacturer-specific data points beyond the standard OBD2 parameters. For owners of vehicles like a 2011 GMC, understanding these enhanced PIDs could unlock access to a wider range of real-time data, possibly including detailed information like oil temperature readings directly from the OBD2 port.
Once the USB ELM scanner is set up, the next phase involves actively trapping communication on the CANBUS. A primary focus is to determine if data points for Tire Pressure Monitoring System (TPMS) pressure and temperature are transmitted from the Body Control Module (BCM) to the Engine Control Module (ECM). Observing data traffic while switching the Driver Information Center (DIC) to the TPMS screen might reveal valuable insights into how these values are communicated within the vehicle’s network. This deeper dive into CANBUS communication is essential for understanding the full scope of data available beyond standard OBD2 parameters, and for DIY diagnostics on vehicles like a 2011 GMC, knowing how to access data like oil temperature via OBD2 is a valuable skill.
The exploration extends beyond engine data and into vehicle control systems. The investigation into an OBD2 window rollup/rolldown module highlights the potential to understand and even manipulate vehicle functions through the OBD2 port. By using an OBD2 splitter cable, it’s possible to sniff the communication sequences involved in lock/unlock commands while the window module is active on the CANBUS. This practical approach to reverse engineering, combined with resources like the car hacking guide and ELM327 datasheet linked below, empowers enthusiasts to truly understand and interact with their vehicle’s systems. For anyone working on a 2011 GMC or similar vehicles, understanding OBD2 and CANBUS opens up possibilities for diagnostics, customization, and deeper vehicle knowledge, whether it’s monitoring oil temperature or exploring other advanced features.
Further reading for those interested in delving deeper:
- A complete guide to hacking your vehicle bus on the cheap & easy – part 1 (hardware interface) |
- A complete guide to hacking your vehicle bus on the cheap & easy – part 2 (interpreting the data) |
- https://cdn.sparkfun.com/assets/learn_tutorials/8/3/ELM327DS.pdf
- http://opengarages.org/handbook/2014_car_hackers_handbook_compressed.pdf
Updates on the progress of this OBD2 and CANBUS exploration will follow as more data is gathered and analyzed. Stay tuned for more insights into unlocking your vehicle’s hidden potential.
