Putting "precooked corn on the cob" on the barbeque?
Putting corn in water only makes sense if it is still in the husk, as that will keep the husks from burning. Soaking precooked de-husked corn would make no difference to you. You can barbecue it, but as it is precooked I'd keep the cooking time down to a couple of minutes, just long enough to heat it up and get a bit of color on it. Any more and it may be overcooked.