1. Correct me if I am wrong ... I was told if I turn on the power switch and headlamp light did not come on but when I start the engine then headlamp light come on MEANS the headlamp is using ALTERNATING CURRENT AC.

2. OK suppose my headlamp is delivering 12V Alternating Current AC to the 35Watt bulb. Now I want to change the bulb to a new 12V of LOWER wattage but higher brightness Direct Current DC LED bulb. Is this possible, are there any complications?