Ford Mustang Owner's Manual page 256

Removing the headlamp bulb
1. Make sure that the headlamp switch is in
the OFF position.
2. Open the hood and locate the headlamp.
Headlamp access covers
3. Remove the electrical connector from the
bulb by lifting the connector clip upward
while pulling the connector rearward.
4. Remove the retaining ring by turning
counterclockwise 1/8 of a turn to free it
from the socket. Then slide the ring off the
plastic base. Keep the ring. You must use it
again to hold the new bulb in place.
5. Carefully remove the bulb assembly from its
socket by gently pulling it rearward without
turning.
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