The CAT 287B is an electronic control module (ECM) used in Caterpillar skid‑steer loaders to manage hydraulic and electrical functions via the joystick pilot system. Common failure modes for this unit include loss of power or signal due to blown fuses, damaged input/output relays, or degraded solder joints on the PCB; intermittent operation often points to worn joystick plungers or faulty wiring harness connections. First‑check steps: verify 24 VDC supply and ground integrity at the ECM connectors, inspect all I/O terminals for corrosion or loose contacts, and review any stored fault codes using a diagnostic scan tool before proceeding with component replacement.[oss-gpt-20b]