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Heavy-Duty OBD IUMPR Data Collection Tool Process — A Practical Guide for CARB Compliance
The Heavy-Duty OBD IUMPR Data Collection Tool Process, defined by SAE Information Report J3162 (2024), provides a standardized software approach for collecting In-Use Monitor Performance Ratio (IUMPR) data from heavy-duty (HD) vehicles. This tool is essential for meeting the requirements of California Air Resources Board (CARB) regulation 13 CCR §1971.1 (l)(2.3.3). By leveraging the widely adopted SAE J1939 family of standards, the process ensures accurate and reproducible data needed for EPA and CARB compliance.
🛠️ Open-Source Advantage: The IUMPR Data Collection Tool software is released under the MIT license and hosted on GitHub, enabling industry-wide collaboration, transparency, and customization.
Understanding the IUMPR Data Collection Tool and Its Purpose
The tool consists of four principal software functions — A, B, C, and E — that run either sequentially or in an order that best fits the planned driving demonstration cycles. Each function interacts with the vehicle via SAE J1939-73 diagnostic messages to read vehicle information, clear or track diagnostic data, and collect performance ratios. The final output is a standardized text file ready for direct submission to CARB.
The table below summarizes each function’s role:
| Function | Purpose | Key Output |
|---|---|---|
| Function A | Select/create a report file and read vehicle information | Verified VIN, CAL ID, CVN |
| Function B | Generate vehicle data plate | VIN, component IDs, calibration IDs |
| Function C | Track monitor completion status | Monitor readiness (completed/incomplete) |
| Function E | Collect test results | IUMPR values and status for each monitor |
🏁 For a valid submission, the first report in the output file must come from Function B, and the last from Function E.
Key Engineering Considerations for Implementation
Modular Design and Flexibility
The tool’s functions are designed to be modular, allowing technicians to run them in an order that aligns with the driving pattern needed to enter specific monitor conditions. This flexibility is crucial for demonstrating that all applicable monitors have run and completed their diagnostic tasks.
Hardware and Communication Layers
Before starting, a compatible vehicle adapter conforming to TMC RP 1210C must be selected from the list shown by the software. The tool supports both 250 kbit/s (SAE J1939-15) and 500 kbit/s (SAE J1939-14) physical layers, automatically querying the vehicle at the appropriate speed. The software claims network address F9h as described in SAE J1939-81.
Definition Priority
When conflicting definitions arise between SAE J1939 and CARB regulation, the CARB document (13 CCR §1971.1) takes precedence. This ensures consistency with the regulatory body’s requirements.
⚠️ Common Pitfall: Failing to verify that the output file’s last report is from Function E can cause the submission to be rejected. Always follow the prescribed order: start with B, end with E.
Practical Steps for Data Collection and Compliance
Vehicle Preparation
Before data collection begins, the vehicle must be prepped by clearing fault codes and resuming monitor statuses using SAE J1939-73 DM11 (clear diagnostic information). This step is typically accomplished through Function B, which sends the DM11 request and generates the initial vehicle data plate.
Running the Functions
After establishing communication via Function A, the operator can proceed with Function B, then perform any necessary driving cycles to enter monitor conditions. Function C can be invoked to check monitor completion status, and when all monitors are ready, Function E collects the final IUMPR measurements.
Example Report Content
The standard includes examples of report excerpts from each function (B, C, E). These illustrate the exact text format required for CARB submissions. The output file automatically includes timestamps, VIN, calibration IDs, and performance ratio results for each monitor.
Frequently Asked Questions (FAQs)
- How does the tool handle conflicts between SAE J1939 and CARB definitions?
According to SAE J3162, the definitions in CARB 13 CCR §1971.1 take precedence where conflicts occur. - What communication speeds does the tool accommodate?
It is capable of collecting data at both 250 kbit/s (SAE J1939-15) and 500 kbit/s (SAE J1939-14) speeds. - Is the software open-source and freely available?
Yes, the IUMPR Data Collection Tool is distributed under the MIT license and is hosted on GitHub for use and modification by the industry. - Can the functions be used in a custom order?
They can be run in the most suitable order for the driving cycle, but the file submitted to CARB must begin with a Function B report and end with a Function E report.
🔍 Engineering Insight: The tool’s reliance on SAE J1939-73 messages (DM11, DM19, etc.) ensures broad compatibility with heavy-duty engines certified to EPA and CARB standards. The modular function design allows flexibility while maintaining strict output formatting for compliance.
