Are H4 bulbs HID?
H4 HID Conversion Kits as also know as 9003 HID Kit. They are the same exact bulb but have two different part numbers. H4 Kits are dual filament bulbs that provide light from your low beams and high beams from the same bulb.
Are 9003 and H4 the same?
As earlier mentioned, the 9003 bulb is almost the same as the H4. However, the two are slightly different, more so in the area of use. As previously hinted, the 9003 bulbs came into the scene to take the role of the H4, which had restrictions.
How do I convert my HID headlights to halogen?
Converting HID ballast headlight to halogen To get the halogen bulbs to work properly in your HID equipped car headlight, you have to install a switching relay behind the housing that directs the constant power for the bulb to one filament or the other.