Citroen C3 Picasso lighting malfunction

[Clive H]

Hi, my wife has a 2015 Picasso 1.6 HDI Exclusive that a couple of days ago seems to have some sort of malfunction with the lighting system.
Normally the lights are left in Automatic mode which works well but we suddenly discovered that in this mode neither the headlights or the DRL's were working although the sidelights and taillights were.
If we switched the lights to manual the DRL's worked but not the headlights or the taillights!
So has anyone any ideas as to what could have caused this and what things to check and in what order to resolve the problem?

Many thanks

Clive

[GiveMeABreak]

First try this as it can fix many electrical niggles:

BSI Reset / Battery Disconnect / Reconnect Procedure

If that makes no difference, then it may well be the Comms unit in the steering wheel that is at fault, but I would suggest a proper diagnostic with Diagbox first as it may be the engine fusebox or more specifically an internal relay within it that are non serviceable.

[Clive H]

Thanks Marc, I'll give that a try first to see if it sorts out the problem. Also what does BSI stand for?
Finally if that doesn't cure the problem would I need to go to a Citroen main dealer to get the diagnostic done i.e is the Diagbox only available from main dealers?

Cheers

Clive

[GiveMeABreak]

It stands for 'Boîtier de Servitude Intelligent'. It's basically the master / controlling computer on PSA vehicles.

A dealer will charge you diagnostic time of course, but then most garages will - but with these sorts of issues it really needs pinning down to whether it's wiring, the BSI, the engine fusebox or the comms unit in the steering wheel.