[JDW3696]

Hello all.
Hopefully you can help with an annoying problem. My car is a 91 240se estate.
The interior light doesn't come on when you open the doors although the light does work when you put it in the on position, to the front of the car and to the rear of the car.
The boot opening does activate the resr light.
I guessed there was an issue with the door switches.
The passenger switch has two wires going to it but the drivers switch only one black and blue wire. Is this normal or is the drivers side door switch missing a wire?
I've cleaned them up but other than that I'm guessing replacements. I haven't checked the rear door switches yet but opening the rear doors does nothing either.
Has anyone got any ideas?
Many thanks in advance
Joe