The MCW102B1085 Grade Controller is a Sauer‑Sundstrand hydraulic grade control module used to regulate pump speed and pressure in hydrostatic systems. Common failure modes for this class of controller include power supply degradation, relay or contactor wear, input signal loss from the motor encoder, and firmware corruption due to voltage spikes. Initial checks should verify that the 48 VDC/24 VDC supply is within spec, inspect all I/O connectors for corrosion or loose contacts, and review any diagnostic LEDs or error codes displayed on the unit’s panel. If power and wiring are correct, test the encoder signal integrity with an oscilloscope and confirm firmware version against the latest release.[oss-gpt-20b]