Accessing vehicle-specific CAN codes through OBDII customization allows for retrieving more comprehensive data than standard OBDII PIDs. This article explores how to uncover and utilize these hidden codes to gain deeper insights into your vehicle’s performance.
Finding Vehicle-Specific CAN Codes
Generic OBDII PIDs provide limited information. Customizing your OBDII setup to read vehicle-specific CAN codes can unlock valuable data not readily available. Resources for finding these codes include:
Online Forums:
- Torque App Forums: A valuable resource for finding codes shared by other users within the Torque app community.
- Vehicle-Specific Forums: Online communities dedicated to specific car makes and models often contain threads discussing custom OBDII codes and data extraction techniques. Diesel truck forums are particularly rich in this information.
Scangauge X-Gauge PID Library:
- The Scangauge website (http://www.scangauge.com/support/x-gauge-commands/) provides a comprehensive library of X-Gauge commands, many of which include vehicle-specific PIDs.
CAN Bus Sniffing:
- If existing resources don’t yield the desired codes, CAN bus sniffing allows direct access to the vehicle’s communication network. This requires specialized hardware and software but allows for capturing and decoding raw CAN data. Resources like Instructables offer tutorials on CAN bus sniffing (https://www.instructables.com/id/CAN-Bus-Sniffing-and-Broadcasting-with-Arduino/ ).
Implementing Custom OBDII Codes
Once the necessary codes are identified, implementing them requires modifying your OBDII interface. Using an ELM327 adapter as an example:
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Setting the CAN Header: Specific CAN headers must be sent to the vehicle’s ECU to access certain data. This can be done using commands like
AT SH 7E0for certain Toyota models. -
Querying the PID: After setting the header, the specific PID can be queried using standard OBDII commands like
21 01.
Decoding the Data
The returned data often comes as a long string of hexadecimal characters. Extracting the relevant information requires careful decoding:
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Identifying Data Position: Determine the precise location of the desired data within the returned string. This might involve trial and error, comparing different readings, and referencing available documentation.
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Data Conversion: Convert the hexadecimal value to decimal or other relevant units for interpretation.
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Verification: Compare the decoded data with known good values from other sources, such as a dedicated sensor or a trusted OBDII application like Torque, to ensure accuracy. Using a serial monitor to log data and then graphing it in a spreadsheet can aid in visualizing and interpreting the data.
Conclusion
OBDII customization through vehicle-specific CAN codes opens a world of possibilities for monitoring and understanding your vehicle. While finding and implementing these codes might require some effort, the wealth of information gained makes it a worthwhile endeavor for enthusiasts and professionals alike.
