rear defrost will not shut-off
 

After driving in heavy rain, the battery was drained, and the light on the defrost switch was on with the car off. 2004 Ion. Hopefully, someone may have a suggestion.

Thanks

Troubleshoot the discharged battery first, the rear defroster will probably correct itself. Heavy rain should not be an issue unless you have been driving through deep water and you have missing under body panels.

Thank you. I will look into this this afternoon.

Ion battery is in the trunk, no?
There are leads that run the length of the car to the front under hood area, so Andy's suggestion is still valid. My comment comes from the thought of a possible trunk leak

I think the battery sits in a vented compartment in the trunk. I suppose water could possibly splash up through the vent and cause problems with the battery.

Yes, the battery is in the trunk.