Key Hole Illumination Check
Measure voltage by backprobing between Smart Entrance Control Unit (SECU) Gray 24-pin connector terminal No. 30 (Red/Yellow wire) and ground. With doors locked, press UNLOCK button on remote controller. Voltage should be zero volts. With button released, battery voltage should be present. If voltage is as specified, system is functioning correctly. If voltage is not as specified, inspect Red/Yellow wire for open or short. Repair as needed. If circuit is okay, replace key illumination unit.