Yea the plugs he is referring to are under/behind the instrument panel. If you loosen the knob and raise/tilt the steering wheel as far up and back as it will go, you should be able to remove all the panel bolts and raise the top enough to access the wiring harness. You are looking for some plastic molded plugs, about 1” square. they will have aluminum label bands on them identifying them as 912 and 913.
If they are plugged together, separate them, set the panel back in place, apply power and see if the dump lights are still lit. If they are cleared, start the truck and see if the charging fail light clears and if your voltages return to a proper 14.1 and 28.2V.