Decoding Isuzu OBD2 Data with ELM327: A DIY Guide

For Isuzu vehicle owners and DIY car enthusiasts, accessing onboard diagnostic (OBD2) data can unlock valuable insights into your vehicle’s health and performance. While dedicated scan tools exist, a cost-effective alternative involves using a cheap ELM327 Bluetooth adapter and a computer. This guide will walk you through the process of manually retrieving and interpreting Isuzu Obd2 data using this setup.

Setting Up Your ELM327 Connection

To begin, you’ll need a budget-friendly ELM327 Bluetooth adapter, readily available online. Pair this adapter with your Windows computer. During the pairing process, you may be prompted for a PIN; typically, “1234” should work.

Once paired, you’ll need a terminal program to communicate with the adapter. PuTTY is a popular and free option. Identify the correct COM port for your Bluetooth adapter by checking Device Manager (look for Bluetooth Serial Port). In the example provided, COM4 was the active port. Launch PuTTY and configure it to connect to the identified COM port.

Sending AT Commands to the ELM327 Adapter

With PuTTY connected, you can now send AT commands to initialize the ELM327 adapter and prepare it to retrieve Isuzu-specific data. Enter the following commands one by one, pressing Enter after each:

• atz – Resets the ELM327 adapter. This ensures a clean start.
• atl1 – Turns line feeds on. This improves readability of the output.
• ath1 – Turns headers on. Headers provide context to the data.
• ats1 – Turns spaces on. Spaces make the data output easier to parse.
• atsp0 – Sets the protocol to automatic. This allows the adapter to automatically detect the correct OBD2 protocol for your Isuzu.
• atsh6c10f1 – This command is crucial and sets the header for Isuzu ECU communication. Specifically, 6c10f1 appears to target the engine control unit (ECU) – ID 10, as opposed to other potential ECUs like ID 18 which may not yield data.

After these setup commands, you are ready to request specific data.

Requesting and Interpreting Data using Mode 22

To retrieve real-time data, we use OBD2 Mode 22, which allows for requesting specific Parameter IDs (PIDs). The command 22194001 is used to request data for PID 1940. The trailing 01 is less clear in its purpose but is included based on previous findings and Scangauge documentation for Isuzu.

Sending 22194001 should return a line of hexadecimal data. In the example, the response was:

6C F1 10 62 19 40 50 32

Let’s break down this response:

• 6C F1 10: These first three bytes are part of the header and receive filter, confirming the communication path.
• 62: This indicates a positive response to a Mode 22 request.
• 19 40: This is the PID we requested (1940).
• 50: This is the actual data byte we are interested in.
• 32: The purpose of this last byte is unclear, but it seems to vary and might be a checksum or status indicator.

To understand the value represented by 50, we need to consult Isuzu-specific PID documentation or resources like the Scangauge X-Gauge documentation, which provides decoding guides and formulas.

Converting Hexadecimal Data to a Meaningful Value

In the example, PID 1940 is related to engine temperature. The data byte 50 is in hexadecimal format and needs conversion to a human-readable temperature value.

Following the provided formula ((A-40)* 1.8)+32 (where ‘A’ is the data byte), we perform the following steps:

1. Convert Hex to Decimal: Convert the hexadecimal value 50 to decimal. 50 in hex is 80 in decimal.
2. Apply the Formula: Plug the decimal value into the formula: (80 - 40) * 1.8 + 32 = 104 degrees Fahrenheit.

This calculation suggests an engine temperature of 104°F. The author of the original post observed plausible temperature readings using this method, further validating the approach.

Conclusion: DIY Isuzu OBD2 Data Access

This manual method demonstrates that accessing Isuzu OBD2 data with a low-cost ELM327 adapter is achievable. By using a terminal program like PuTTY and sending specific AT commands and OBD2 Mode 22 requests, you can retrieve valuable data from your Isuzu vehicle.

While this method is manual and requires some technical understanding, it offers a budget-friendly way to explore your Isuzu’s diagnostic information. Further exploration and scripting with tools like Arduino or Raspberry Pi could automate this process and create a custom Isuzu OBD2 data display for real-time monitoring. Remember to always consult relevant documentation and resources for your specific Isuzu model and PIDs for accurate data interpretation.