Seicento owners see here:
https://www.fiatforum.com/cinquecento-seicento-guides/89724-rear-light-bulb-replacement.html

Tools:
  • Crosshead Screwdriver
**Note to LED bulb Users**
Your Load resistors for direction indicators should come with simple electrical connectors which just clip onto the existing wires(like the brown connector in the picture), I however did not have these, so used a screw block thingy!
Lrs.jpg

Let's Begin:

Firstly, open your boot! Now you will see each light cluster has two screws above it, undo these by screwing anti-clockwise (don't lose the screws). Now the light cluster will need some jiggling and some upward pushing to remove it from it's hole.
old cluster.jpg

Now you have removed the light cluster from it's hole, you can fully remove it from the car by unclipping the electrical connector.
old cluster off.jpg
If you are changing a bulb, all you need to do is unscrew the two screws in the black plastic to gain access to the bulbs.

**LED Bulb Users only**
Got LED direction indicator bulbs? They will flash too fast unless you wire in a load resistor before each cluster. They are wired between the ground and the live for the bulb. The ground is Black on each side, and the Live is Light Blue and Black on the passenger's side, and Light Blue on the Driver's Side.
load resistor wiring.jpg

All Done with your Lights? Let's put them back in:

The lights go back in exactly the same way they came out, only in reverse, so get the hooks at the bottom into the hole then have a jiggle around. Then screw them back in by screwing clockwise.
yellow cluster in.jpg

**Note: It is important you make sure the lights are fitting flushly and have a good seal to the bodywork, as it is a common area on cento's for water to get in.**