Check all bulbs are working.
Front:
2x Dipped/Main beam
2x Sidelights
2x Indicators
2x Front fogs (if fitted)
Rear:
4x Sidelights
2x Brakelights (on the lower bulb of the sidelights)
1x Centre brakelight
2x Indicators
1x Reverse
1x Rear fog
2x Numberplate lights
Check all of the above. If they are lit, they will be fine. If they are dim, replace the bulb.