Good to see this resolved!
I had the "reverse" situation - my third brake light would light, but the 4 brake lights (though left/right, and driving lights (lower power 'ON' all worked).
Problem turned not to be the brake switch, but a small 37uF capacitor across the connection (blue and orange wires, I think I remember it as, but don't rely on that from my memory!). I replaced the capacitor and they all worked again. Either a lose or shorted connection.
This was on a 92, I seem to remember at the time that this was put on in 92 (so may not be there on the 90) to cope with arcing potentially messing up the ABS and ASR...
Anyway, just my 2c, but if a new brake switch fixed it - good and glad to hear it
