The fog switch on the dash is just that will turn on sidelights and front fogs , there should be a separate aftermarket switch either around the dash cowl or binnacle . jap cars had no requirement for a rear bog , many once they came over either had an unsightly lamp hung on the back or the cheap quick mod was to turn one of the reverse lights into a fog , as Scott says there are a few workarounds for this including the rear lights becoming fogs
Craig 