If your battery is showing 12.8 volts (This is fully charged) but the hot wire to your relay is only showing 12 volts, then there is a problem with the wiring between the battery and relay box.
A battery at 12.8v is fully charged, a battery at 12v is fully discharged.
I would clean and tighten the battery terminals then start following the wiring from the battery to see where the problem is.
Tuesday, September 20th, 2011 AT 7:54 PM