1987 toyota pickup

i just got a 87 toyota pickup 22r. the truck wont shift into overdrive, previous owner said it ran low on trans. fluid. I heard that trans. ecm shift also works off of the engine temp? could it be preventing my O.D shift, truck runs cool, they took out the thermostat? what else could it be? :uhoh:

i just got a 87 toyota pickup 22r. the truck wont shift into overdrive, previous owner said it ran low on trans. fluid. I heard that trans. ecm shift also works off of the engine temp? could it be preventing my O.D shift, truck runs cool, they took out the thermostat? what else could it be? :uhoh:

okay scratch the running cool issue, put a new t-stat, trans still wouldn't shift into o.d