I found a way to fix the dome light in my S90 -
all you need is a pencil eraser, WD40, and an aluminum "fence tie" which you can buy at hardware stores (look in the chain link fence section)

- Unplug the light and vacuum line
- Using an Xacto knife, cut the "mushroom" heads off of the plastic pins that hold the circuit board to the light housing, indicated in the photo here by the yellow dots
- Also cut the plastic off the top of the brackets on either end of the small circuit board (not shown in photos)
- Remove both boards together ... you do NOT have to remove the black climate control sensor
- With the boards removed, you will see the metal fingers on each switch
- Bend the fingers up slightly and clean the contact tips with a pencil eraser
- Clean the copper contact pads on the circuit board with the eraser. There may be some electrical grease on the board
- Apply some WD40 to the finger tips and contact pads
- Insert both boards and press them down over the trimmed plastic pins (marked in yellow)

- Now carefully drill a hole in each of the 2 front (vehicle front) "legs" which hold the dome light in the headliner. (I used a hand-held power screwdriver with bits that fit in the screwdriver)
- Use a bit size that will allow the fence tie to slide through easily but not sloppily
- By drilling at the spot shown in the second photo, the aluminum rod will slide under the 2 lamp sockets
- Slide the fence tie (highlighted with a red line on the photos) through both holes
- Trim the fence tie so that it does not stick out past the legs when they are squeezed together.

- The aluminum rod will keep the circuit board from popping up when the switches are pressed. If necessary, slip a piece of folded aluminum foil between the fence tie and the circuit board as a shim. Do NOT use paper or plastic


http://www.brickboard.com/GALLERY/volvopic.htm?js_link=&id=11348

http://www.brickboard.com/GALLERY/volvopic.htm?js_link=&id=11349