Both of my Toyotas('87 pickup and '98 T-100) have this valve but I've never touched either one.
You might be able to disconnect it from the rear end and lift the arm up to open the valve.
I am thinking that I might use a ratchet strap to pull the bed downward toward the axle to open the valve and therefore be able to bleed everything.
Obviously Toyota thought this was a great idea because they've been using it in all of their truck since the beginning of time. Seems super weird to me but if I had my choice of throwing a Japanese engineer or a General Motors engineer off the bridge... it sure would not be the Toyota guy.
