The Yanmar 3TNV88F‑EPHB 129017‑75030 is an electronic control unit (ECU) that manages fuel injection, timing, and emissions for the 3TNV88F water‑cooled diesel engine. Common failure points in this class of ECUs include burned or cracked silicon on the main power MOSFETs, damaged I/O driver ICs, and corrosion or mechanical damage to the high‑current PCB traces that carry the fuel pump and injector signals. Initial checks should verify the 12 V/24 V supply rails against the service manual specifications, inspect for visible burn marks or cracked components on the board, and confirm all connector pins are clean and fully seated before proceeding with a continuity test of the high‑current paths.[oss-gpt-20b]