The IPDM has separate fuses for each side, and will have the high and low beam relays soldered to the circuit board.
I don't have e12 manuals but there is one online here
Nissan Note E12. Manual - part 472
There is so much to go wrong, it could be a fault with the combination switch, a faulty connection to the switch, a broken wire, CANBUS error, wires from the IPDM, connectors on the IPDM, the IPDM itself, the IPDM internal relay.......
If you had the Nissan service dongle you can trigger the IPDM functions and test it. I think something like the Topdon Topscan Pro can trigger the outputs for testing too.