I have a 1989 xjs soft top, The idiot light is always on when i drive with lights on. I checked all my lights and they all work. However, all my controls that light up using fiber optic do not come on. Is the fiber optic bulb connected to the idiot bulb for lights out,

 

207 was the OE Lucas generic bulb part number.

Narva used 47207 as their Part Number.

Used on most cars/trucks etc, and not unique to Jaguar in any way.

Some have gone LED, I have not.

 

The fibre optic bulb is not part of the lights-out warning light circuit.

 

The bulb failure circuits are linked to front sidelights, rear taillights and number plate lamps (and also brakelights).

if the failure light stays on after more than 30 seconds with sidelights on, then you'll have a bulb problem in one of those bulbs. Have you changed any of them for LEDs, as this will cause the problem?

Paul