My 01 dodge 2500 4wd diesel engine pu has started dischargeing the batteries while parked. I disconected the batteries and connected a volt ohm meter between the + and - battery clamps. There is a ground or short somewhere. I started pulling fuses and found that by removeing 4 fuses from the fuse box under the hood the meter will show 0 or an open circuit. If I replace any one of the 4 fuses the circuit closes and the short returns. The fuses are, (1) 20 amp engine control 2, (2) 20 amp hazard, (3) 40 amp trailer, (4) 40 amp abs. Any idea on how or where these circuits interact or system that could cause all 4 to short at the same time?

thanks bill