The Sauer Danfoss MC300 is a micro‑controller based hydraulic transmission controller designed for dual‑path hydrostatic propulsion and closed‑loop speed or horsepower control, with support for up to four bi‑directional servo loops. Common failure points in this class of units include power supply degradation (overvoltage/undervoltage), overheating of the MCU or driver ICs, and loss of communication on the CAN or serial bus due to cable damage or connector corrosion. First‑check diagnostics should verify that the unit receives its rated input voltage and current, inspect all I/O connectors for continuity and proper torque, and review any stored error codes or watchdog resets via the diagnostic port before proceeding to board‑level inspection.[oss-gpt-20b]