The 4M51 ECU typically uses a multi-plug aluminum-case housing. While minor color codes vary by production year (e.g., Fuso Canter FE639 vs. FE659 models), the functional pin groups remain highly consistent.
Most 4M51 ECUs use two multi-pin connectors (commonly labeled A and B). Pin numbering is shown as connector:pin (e.g., A1). mitsubishi 4m51 ecu pinout work