Based on the 9WM prefix posted on an earlier thread this is what the O&M Manual says ...........
View attachment 251972
It's a pretty simple parking brake, manually applied with a cable. I would question if the switch that applies the "Brake on" light is defective or alternatively not adjusted correctly. If that's not the case then maybe the neutral signal from the transmission control direction has gone AWOL.
The parking brake is on the rear side of the front axle housing. The braking force is applied with a lever and a cable assembly. The parking brake is manually actuated. This is done by pulling upward on a lever assembly that is operated by hand.