CDL Bus Light & Signal Check – Step-by-Step Guide In this CDL training video, we walk through how to properly check signal lights, high beams, four-way flashers, and emergency lights on a school bus as part of your pre-trip inspection. You'll also see how to activate the stop arm and safety arm using the master switch and passenger door. This is a key step in ensuring all lighting and safety equipment works correctly before transporting students. Whether you’re preparing for your CDL test or bru