Vauxhall ASTRA Owner's Manual page 291

286 Self-help
5. Remove the round seal from the
fastening bolt. Press the locking tabs on
the outside of the bulb holder outward
and remove the bulb holder.
Bulbs in bulb holder:
1 = Reversing light
2 = Turn signal
3 = Tail light/brake light
4 = Tail light
5 = Fog tail light
6. Remove bulb from socket.
7. Insert new bulb, without touching the
glass.
8. Engage bulb holder in bulb housing,
ensuring that it properly engages.