From what I've found, the P1684 Code means that the ECU has lost voltage within the last 50 starts. This could be from disconnecting the battery, a loose or corroded connection, or even a weak battery from repeated or long cranking.
The 2002 Dodge Grand-Caravan has a V6 engine.
The 2004 Dodge Grand-Caravan has a V6 engine.
The 2012 Dodge Grand-Caravan has a V6 engine.
The 2008 Dodge Grand-Caravan has a V6 engine.
The 2010 Dodge Grand-Caravan has a V6 engine.
The 2005 Dodge Grand-Caravan has a V6 engine.
The 2007 Dodge Grand-Caravan has a V6 engine.
The 2014 Dodge Grand-Caravan has a V6 engine.
The 2009 Dodge Grand-Caravan has a V6 engine.
The 2011 Dodge Grand-Caravan has a V6 engine.
The 2001 Dodge Grand-Caravan has a V6 engine.
The 2013 Dodge Grand-Caravan has a V6 engine.