So I've had this problem for a while. I researched the issue especially on this forum and I thought that part number 6554ZZ was my switch to change out.
I decided to have a look at my switch to confirm, and it took a while to get to it as it was my first time and those clips are a nightmare until you get a feel for them.
My main panel has 2 plastic push screws. Pull out the middle tab and turn and pull. There are 2 star metal screws in the hand panel. It's then a matter of forcing off the panel. There are 12 hidden clips. It seems the panel is breaking when they come out.
The next item is the outside trim which includes the number plate. Use a 10mm spanner or socket to remove the 5 metal screws. This outside panel is held on with 8 hidden clips like the main panel. Again you will think you are going to break something as they pop out. When the panel is off the 2 number plate light cable connectors and the switch cable connector need to be disconnected so the panel can be put aside.
The little switch that failed can just be slid out on the panel. I doubled checked that it was a faulty switch by using a paper clip in the connection and the lock worked perfectly. There was evidence of water in the switch, probably from power washing the car.
The switch was not 6554ZZ as I first thought. Some places list this switch for a pre 2013 C4 Picasso. A bit more research and it's a 6490R3 which doesn't get much mention as a problem item.
I did notice once the panel was off that the outside switch/handle can be taken out. A little fiddly with 4 plastic tabs. If the cable was long enough (mine wasn't) this would be the easiest way to change the switch rather than taking all the panels off.
I do have some pictures but they are too large to upload.
Hope this helps someone.
I decided to have a look at my switch to confirm, and it took a while to get to it as it was my first time and those clips are a nightmare until you get a feel for them.
My main panel has 2 plastic push screws. Pull out the middle tab and turn and pull. There are 2 star metal screws in the hand panel. It's then a matter of forcing off the panel. There are 12 hidden clips. It seems the panel is breaking when they come out.
The next item is the outside trim which includes the number plate. Use a 10mm spanner or socket to remove the 5 metal screws. This outside panel is held on with 8 hidden clips like the main panel. Again you will think you are going to break something as they pop out. When the panel is off the 2 number plate light cable connectors and the switch cable connector need to be disconnected so the panel can be put aside.
The little switch that failed can just be slid out on the panel. I doubled checked that it was a faulty switch by using a paper clip in the connection and the lock worked perfectly. There was evidence of water in the switch, probably from power washing the car.
The switch was not 6554ZZ as I first thought. Some places list this switch for a pre 2013 C4 Picasso. A bit more research and it's a 6490R3 which doesn't get much mention as a problem item.
I did notice once the panel was off that the outside switch/handle can be taken out. A little fiddly with 4 plastic tabs. If the cable was long enough (mine wasn't) this would be the easiest way to change the switch rather than taking all the panels off.
I do have some pictures but they are too large to upload.
Hope this helps someone.