It depends on whether you have HID lights or Halogen Lights. See sources and related links below.
According to the 2004 Ford Expedition Owner Guide : Low beam headlights take ( # 9006 bulb ) High beam headlights take ( # 9005 bulb )
The Low Beam AND High Beam are in the same bulb. The procedure to change it will be in the owners manual.
You can access the low beam headlight bulb from the engine compartment. Push the bulb holder in and turn. The bulb will come out.
Low Beam Headlight Bulb Size: 9006High Beam Headlamp Light Bulb Size: 9005
There may be a poor connection or a burned out fuse for the driver's side headlight. There may be a poor connection or a burned out fuse for the driver's side headlight.
In a lot of newer cars, you pop the hood and twist off the bulb-holder from behind the headlight. Then, you remove the old bulb, insert the new bulb, and twist the bulb-holder back into the headlight. In some cars, you have to replace the whole headlight.
What vehicle is this for?
9006 for the low beam 9005 for the high beam
low beam headlight bulb type: 9006
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H1 55W bulb