PS9 ECU Technical Overview
Technical overview of the PS9 ECU used in 1990-1991 USDM Honda Civic EX models, featuring integrated automatic transmission control.
The PS9 ECU was utilized in 1990â1991 USDM Honda Civic EX models equipped with the 1.6L SOHC engine.
Note
The PS9 hardware architecture is functionally identical to the PM6 ECU, with the addition of dedicated circuitry required to manage an automatic transmission.
Hardware Specifications
The PS9 is primarily distinguished by its integrated transmission control unit (TCU) functionality. When servicing or tuning this unit, refer to the following comparison:
| Feature | PM6 | PS9 |
|---|---|---|
| Engine Compatibility | 1.6L SOHC | 1.6L SOHC |
| Transmission Control | Manual | Automatic |
| Architecture | OBD0 | OBD0 |
Technical Documentation
The following image provides a visual reference for the PS9 PCB layout and component identification.
Digital scan of the USDM PS9 automatic ECU PCB
Important
Ensure all modifications to the PS9 board are performed using appropriate ESD-safe equipment. Because the PS9 shares the same base architecture as the PM6, standard OBD0 tuning procedures apply, provided the transmission control logic remains undisturbed.