I could use some help. I have 2004 6.0 that drains batteries in 12 hours. tested both batteries with a battery load tester they are good. I disconnected both grounds and clamped a dvm between one battery ground post and the negative battery cable. the meter set at 20dcv with the key off reads 6.21v. shouldn't it be zero or near zero? I then pulled every fuse/relay under the drivers dash, the two relays near the brake booster without any significant change on the meter. I also unplugged the alternator completely without any change..................

 

Look at the starter...
Any leaks from windshield ?

 

No leaks. Starter is new and I had this problem before the new starter. The starter wires LOOK ok any way to test those??