Haynes for Zaf says is one of:
Bulb Blown, Corrosion of Bulb or contacts, Blown Fuse, Faulty Relay, Broken loose or disconnected wiring, Faulty Switch.
Fuses are in the LHS Luggage compartment or the Fuse/Relay box in the engine compartment.
I just happened to have the manual and looked that up ... otherwise I'm a novice at this stuff.