156 Rear Side Light Problem

[werdfer]

My nearside rear side light and offside front side light are both off when the lights are on, also the bulb warning light is on the dash constantly, I have tried new bulbs but still no good. I understand that this points to a blown fuse, but the fuse is good and when I remove the fuse the bulb warning light goes out. Does anybody know of a wiring diagram for the 156 or a resolution to this problem. Any help would be apreciated.