one for nigel to ponder?

Saxo 1.1 no oil warning light.no over temperature light sensor warning bulb when ignition turned on only the fuel gauge working clock illuminations o k,all fuses o k

BEST way to test and find the problem as Haynes manual u s
could a faulty oil pressure switch also take out the over temperature sensor ,can i bridge out to do a test on the bulbs save stripping dash out been a long time since they worked but do know engine pumping oil around
remove lead from oil light replaced with a test light up oil light connection, other end to earth,
Turn ignition on ALL lights illuminate (ponder do i start engine ) go for it lights go out except oil light and over temp light .to me my test light has acted as a link wire proving oil pressure switch is o/c