No hook ups on a JO2,These are the Pre-computer day trucks.

Check and fill the radiator resevoir bottle, if light stays on disconnect wires to confirm light goes out, most of the time the sensor float in the bottom of the bottle sticks, you can stick a low air pressure blow gun (20-30 psi) into the bottle and give it a couple of quick shots of air and that frees up the float. If not replace the entire bottle assy.

Also check LP tank bracket release micro-switch on top left side of counter weight.