Turn the key to the ON position and check whether the dashboard lights come on
Turn the key to the START position and check whether the engine cranks
Wiggle the key gently and see whether power cuts in and out
Test whether accessories such as radio, blower, and lights work in the ACC and ON positions
Check for intermittent starting or no-start issues when turning the key
Inspect the ignition switch connector for loose, corroded, or damaged terminals
Use a multimeter to verify voltage at the ignition switch input and output terminals
Compare switch output in OFF, ACC, ON, and START positions
Check for continuity across the ignition switch terminals according to the vehicle wiring diagram
Inspect the key cylinder and switch linkage for wear or binding
Replace the ignition switch if voltage, continuity, or operation is inconsistent