There are switches all over the T-case to indicate where it's positioned. Someone said 11 switches in total to me once with the backup light switch. They all seem to be alike but have either N/O or N/C operation. I'm guessing your 4lo switch is out and not feeding voltage to the control unit.

1987 SWB Pajero 2.5 TDI on 31" rubber waiting for a hip replacement and bigger shoes