The Sevcontrol MOS90 631/40038 is a DC traction and pump controller that integrates MOSFETs with microprocessor control for small‑to‑medium electric vehicles such as pallet trucks and low‑capacity forklifts. Common failure modes reported in the MOS90 manual include over‑temperature shutdown, loss of communication on the CAN or RS‑485 bus, and failure of the high‑current MOSFET array due to thermal cycling or voltage spikes. Typical diagnostic steps are: verify that the input supply is within spec (12–48 VDC) and that the controller’s status LEDs indicate normal operation; check all I/O connections for proper polarity and continuity, especially the motor drive terminals and any external relay contacts; review the fault code register via the serial or CAN interface to identify specific error codes such as “E01 – Over‑temperature” or “E02 – Communication timeout.”[oss-gpt-20b]