Do they stay on or do they continually flash, as if the lever is in "Right Turn"?

If they are on steady, I'd suspect the CLP/SSM (Central Locking Pump/Security System Module) in the rear passenger side wheel well. It has probably been exposed to water, this is a common complaint. You can yank the connector from the module, if they go out, there is your issue - if they stay on, we have more homework to do.

If they blink, I'd suspect the Multifunction Switch.