On: Self driving 1993 Volvo with open pilot

[Ccecil]

I am not sure about that particular car but some cars have a electrically switched valve on the power steering pump which lowers the pressure for higher speed travel (less responsive). You may be able to get "some" control just by disconnecting this (assuming it is there, my 93 Mazda 626 had one).

[UniverseHacker → Ccecil]

No, the power steering system on these is entirely hydraulic/mechanical. I’m surprised Mazda had such a feature so early.