While OBD2 ports typically have Tx and Rx terminals for communication, these are often not connected on older Subaru ECUs like the Version 5/6. This guide outlines how to establish an RS232 connection directly to the ECU for diagnostics and tuning.
Connecting to a V5/6 ECU requires accessing the correct pins on the ECU itself, specifically pin 3 and 4 on connector 136. These pins correspond to the Tx and Rx lines for data transmission and reception. Often, these pins are not populated with wires from the factory.
Accessing these pins requires opening the ECU casing. Exercise extreme caution when doing so, ensuring the battery is disconnected and all necessary static precautions are taken to avoid damaging the sensitive electronics. Once open, carefully solder wires directly to pins 3 and 4. A low-heat soldering iron is recommended to prevent damage.
Route these newly soldered wires through the unused third connector hole on the ECU casing. Drilling small holes may be necessary to accommodate the wires. A simple connector, such as a chocolate block connector, can be used to terminate the wires externally. This provides a convenient point to connect your Rs232 To Obd2 adapter.
When wiring, use different colored wires for Tx and Rx to avoid confusion. Ensuring correct polarity is crucial for successful communication. Connecting the Tx line to Rx and vice versa will prevent data exchange. Double-check your connections before powering on the ECU.
Once the connection is established, software like Log1Call can be used for data logging and analysis. Remember, handling the ECU requires care and attention to detail. Always disconnect the battery before making or breaking connections. With proper precautions and the steps outlined above, a successful RS232 connection to your Subaru V5/6 ECU can be achieved.
