Recently, Solid State Relay (SSR) using Power MOSFET or Intelligent Power Switch (IPS) has been increasingly used in automobile industries. Comparing with the mechanical relay, SSR offers relatively higher switching speed and reliability by its non-contact structure and self-protection function. Because of these outstanding features, SSR is often used in engine and safety control systems. A new SSR system for rear lamp control, which can offer higher levels of power line protection against overcurrent than conventional fuses. The SSR system has been developed utilizing Power MOSFET with a built-in overheat protection circuit (PW-MOS), high precision Current Sensing Resistor and newly developed Driver IC. The system functions and verification results on major issues are described as well as the future goals of such SSRs.