2004 landrover discovery td5 courtesy light

My landy front courtesy light is not on with key on ignition in case the switch is turned on. After I insert key or open a door, the light is on by default, if I turn the switch on/off, the light is off, it indicates the switch on can work. I can not use the light during a ride. But the rear courtesy light is okay. Please share your idea with me.

Electrically, the front and rear courtesy lights are the same, the rear loadspace light is different in that it doesn't have a manual switch.
You should be able to see from the diagram, there are three wires fed to the front and rear lights. The black wire is a permanent earth, the purple wire is a permanent +12 volts and the purple/blue wire provides the switched earth from the BCU.
Since the wiring to and the operation of the rear light appears to be correct it would appear that you probably have a problem with the permanent earth or the switch in the front light unit.

Thanks brian47, I found the black wire was connected to sunroof motor when I changed the sunroof motor before.