PM9 ECU
The PM9 is essentially a variant of the PM5 ECU, with differences primarily related to transmission type (4-speed vs. 5-speed) and processor architecture across model years.
Overview
The PM9 is essentially a variant of the PM50 ECU. The PM5 and PM9 are fundamentally the same ECU platform, with primary differences related to transmission type and processor generation across model years.
Important
PM5 and PM9 units employ two distinct processor designs similar to the PG70. Early models (1988â1989) use an
83C154processor, while later models (1990â1991) use a66201processor. The 1990â1991 processor configuration closely resembles OBD1 ECU architecture.
Variants and Transmission Compatibility
| Model Year(s) | Processor | Transmission | Notes |
|---|---|---|---|
| 1988â1989 | 83C154 | 4-speed / 5-speed | Earlier design variant |
| 1990â1991 | 66201 | 4-speed / 5-speed | OBD1-style processor layout |
The PM9 units documented were sourced from Honda Civic HF models with 4-speed transmissions, suggesting a potential correlation between ECU variant and transmission type, though this relationship is not definitively confirmed.
Physical Reference Images
