The Lightolier CL45II is a four‑channel industrial controller designed for process or temperature regulation, typically using an RS‑485 interface and internal relays to drive up to four output loads. Common failures on this model include degraded power‑rail traces or blown capacitors in the 12 V supply section, contact wear or burn‑out in the relay contacts, and firmware corruption that can cause the unit to lock up or report erroneous status codes. Initial checks should verify the input voltage and regulator output with a multimeter, inspect the relay coils and contacts for signs of arcing or corrosion, and review any logged error codes via the RS‑485 diagnostic interface before proceeding to component replacement.[oss-gpt-20b]