For DIY enthusiasts and budget-conscious car tuners, understanding the Obd2 Pinout Diagram is crucial when undertaking ECU conversions. This guide provides a clear OBD2 pinout diagram specifically designed for those performing an OBD2a to OBD1 conversion, particularly when utilizing a P28 Uberdata ECU or similar OBD1 ECUs like P30 and P72.
Below is the wiring diagram detailing the connections required for an OBD2a to OBD1 conversion harness. The OBD1 pinouts are listed on the left, and the corresponding OBD2 pinouts are on the right. This diagram simplifies the process, making it accessible for those who prefer to handle their modifications in their garage.
| OBD1 Pinout | OBD2 Pinout |
|---|---|
| A1 | A4 |
| A2 | A1 |
| A3 | A3 |
| A4 | A8 |
| A5 | A2 |
| A6 | A6 |
| A7 | A16 |
| A8 | no use |
| A9 | A12 |
| A10 | no use |
| A11 | no use |
| A12 | A27 |
| A13 | A18 |
| A14 | no use |
| A15 | A17 |
| A16 | A19 |
| A17 | A26 |
| A18 | no use |
| A19 | no use |
| A20 | A15 |
| A21 | A20 |
| A22 | no use |
| A23 | A10 |
| A24 | A23 |
| A25 | A11 |
| A26 | A9 |
| B1 | A24 |
| B2 | A22 |
| B3 | no use |
| B4 | blank |
| B5 | C5 |
| B6 | blank |
| B7 | C29 |
| B8 | C16 |
| B9 | C6 |
| B10 | C18 |
| B11 | C4 |
| B12 | C14 |
| B13 | C3 |
| B14 | C13 |
| B15 | C2 |
| B16 | C12 |
| D1 | C10 |
| D2 | D5 |
| D3 | D6 |
| D4 | C7 |
| D5 | no use |
| D6 | C15 |
| D7 | C8 |
| D8 | no use |
| D9 | C17 |
| D10 | D16 |
| D11 | D1 |
| D12 | no use |
| D13 | D2 |
| D14 | D7 |
| D15 | D8 |
| D16 | no use |
| D17 | D3 |
| D18 | no use |
| D19 | D4 |
| D20 | D10 |
| D21 | D12 |
| D22 | D11 |
This OBD2 pinout diagram is also compatible with P30 and P72 ECUs, as well as other OBD1 ECUs, offering versatility for various Honda and Acura models.
For those sourcing parts, remember that OBD2 plugs from automatic transmissions are excellent for this conversion. They often come with extra pins, which can be invaluable when replacing shorter pins during your DIY conversion harness build.
