Hi,fellow bricksters

You,ve saved my behind before and i am hoping that you would again please.
My (wife's) problem:1990 745 GLE (16 valve) brake lights don't come ON
light bulbs look OK but i replaced them any way,the brake light on the rear window doesn't light either.
Turned ON the lights they all work fine, but not bright ilumination when
i step on the brakes, and the idiot-light comes ON for bulb failure,but when
i turn the light switch OFF, the idiot-light disapear.
Everything seems to work (turn signals, back-up lights, head-lights, etc)
but NO BRAKE LIGHTS.
I took the cover out-under the steering column-and there is a switch with
two thin wires on a conector, an d a thin black hose atached to the swich.
Went to my friendly Volvo dealer who is giving me a very different looking
switch without a hose bib and two large conectors, that even I know it's
the wrong switch,
Please help me trouble shoot this mystery, in as simple as you can
becase amps and ohms are all Greek to me.
The dealer is telling me there is no relay but the BRICKBORD'S FAQ says
the opposite

Thanks and Happy Holidays . Gatos