PM6 ECU (OBD0) Hardware & Code Reference
Detailed hardware specifications, pinouts, and custom codebase support for the OBD0 PM6 Civic/CRX Si SOHC ECU.
Adapted from pgmfi.org wiki
The PM6 is the factory OBD0 engine control unit (ECU) utilized in 1988–1991 USDM Honda Civic and CRX Si models powered by the SOHC 1.6L D16A6 engine.
Due to its simple architecture and widespread availability, the PM6 has historically served as a major development platform for OBD0 Honda tuning, disassembly, and real-time programming.
Microcontroller Architecture
The PM6 ECU is built around the OKI 83C154 / Intel 80C154 microcontroller family. The ROM code can be extracted, modified, and burnt to standard EPROMs (such as the 27C256) to adjust fuel maps, ignition maps, rev limits, and other engine parameters.
Development Resources
The following development files are co-located in this directory:
- Pm6.asm: A comprehensive disassembly of the USDM 1991 PM6 stock ROM, with approximately 95% of the original assembly code fully mapped and commented for developers.
Board Layout Reference
Below are high-resolution scans of the PM6 ECU printed circuit board (PCB) for component mapping and repair reference:
1. Board Top Layout
The top side of the PM6 PCB showing IC locations, capacitors, and resistor packs:
2. Board Underside Layout
The rear solder side of the PM6 PCB:
Credits and source
Authors blundar, drdisco69
Source Adapted from PM6 on pgmfi.org wiki. Licensed under CC BY-NC-SA 1.0.