Drove through water and cant locate problem...?

Your battery terminal may have gotten wet and corroded. You can take off those leads and scrape the corrosion with a knife or file. Other likely culprits are the alternator terminal and grounding points, the alternator itself which may have been damaged from the water, the junction box with all the fuses and relays which are actually pretty sensitive, your distributor, or electrical grounds . Basically what you should do is estimate on the van how high the water came up to, and then look under the hood at what may have gotten wet. Whatever was near that water line, disconnect the connections and clean them, or replace them. If you live in a wet climate or anticipate doing this again, consider using a bunch of dialectic grease on those connections.