1993 diesel dash light problem

[dorset yokel]

hi all upon turning on ignition all usual lights come on ok when started alternator light goes off ok but the overheat temp light and oil pressure light stays on does flicker when revved but does not go out
have tested alt and all ok if you turn ignition off when rolling and bump start lights stay out until u get back to idle
any info would be very grateful as now starting to pull hair out hope someone can help