My voltage gauge on my 2003 Dodge pegged to nothing while driving the other day. I measured battery voltage with a seperate meter with the engine running and it read 12.25 volts. Later, the dash gauge read good voltage and the battery read over 13 volts with a sperate gauge. The guage pegged to nothing again the next day. I pulled out the alternator and the repair shop stated it looked good but the altenator has the voltage regulator externally built into the ecm. I am wondering if anyone has tried to install a seperate external voltage regulator or had the same problem? I wiggled the wires next to the alternator with no effect.