4000csQ reverse lights

[Marc Swanson <marc@lodoss.mv.com>]

        I have an 87' 4000cs Quattro and my reverse lights stopped working a
while back.  I checked the socket and there is no power going to the reverse
light assembly with the key on and the transmission in reverse.  In the
documentation there is no mention of which fuse or relay controls the
reverse lights.  Could it also be the reverse switch?  If so, where is that
located?
                                                               Thank You
                                                                -Marc-