Nissan Repair: 1992 Pathfinder, amp meter, milliamps

Question
Hi Calvin, I have a 1992 Pathfinder with a manual transmission and a battery drain problem, a few weeks ago something started to make a funny noise coming from what seemed to be the passengers side of the engine as I was driving home this noise continued, along with the heater and lights going off and coming on again.This continued to happen all the way home. The next day, it would not start (completely dead). We thought that it was the alternator, so we replaced that and there was no change. So then we had the starter tested and were told that it was bad, so we replaced that. It then started but the battery will  not hold a charge.After about 3 hours the battery is completely drained. We took the battery and had it tested and was told it had a bad cell, so that too was replaced. There is still no change. It starts, it runs, but if we don't take that battery cable off its dead. The headlights seem to be playing a roll in this too,there is no change between the day lights and headlights when I turn them on. There is power in the circuit on the drivers side and no power in the circuit on the passengers side, which one is right could the drain be from one or the other and which one (tested with the light switch in the off position).  Can you give us any suggestions, I would really appreciate any help I really miss my pathfinder. I hope that I have not been too long winded but I hope that the more you know... is better. Thanks for your time and I look forward to anything that might help.   
                            Sadie

Answer
Hi Sadie -

Yes, thanks for the detailed information. With the vehicles not in my reach, it is hard to diagnose, so thanks for the info.

Pathfinders seem to be famous for battery drain, I get a lot of these. But with yours, battery draining in 3 hours, that is a first . . .

The first thing we should do is try to determine where the drain is coming from. For this you will need a amp meter that measures milliamps, or MA. Remove the negative side terminal of the battery, wait at least a minute, and then connect one lead of the amp meter to the negative side of the battery, and the other to the terminal that was just removed. Note the reading. If it reads more than 35 MA, then you have a battery drain somewhere. The best way to locate this drain is to remove each fuse one by one and note the reading to see if the drain is still there. Once you locate the fuse that stops the drain, then you will know which circuit to pursue. It is quite detailed and cumbersome, but this is the only way to trace this.

Please let me know how this goes -

Hope this helps -
aloha
calvin