Intermittent Parasitic Drain on 2014 6.7
 

I have a 2014 6.7L with 130k miles on it. Deleted, but otherwise stock. No aftermarket electronics or lighting. The truck was fine for the first 4 months, but over the summer it started to intermittently die and have to be jumped. Sometimes it will happen overnight, sometimes in a few hours, sometimes it can sit for 4 days and crank right up.

Once it's jumped, the truck is fine for a week or even several weeks. The problem is inconsistent enough that I have had trouble diagnosing it. The truck has a new starter and batteries.

I've tried running a parasitic drain test, but can't catch the problem while it's happening.

1. Does it matter which battery I use to test? The passenger side battery seems to draw about 40 milliamps after all the modules go to sleep. From what I've seen online, that's in the normal range? The driver side battery doesn't draw anything after it's all been shut down for 30+ minutes.

After shutting the truck off, the batteries draw around 130 milliamps for about a minute, then it drops to 80-90 for a couple minutes, then down to around 60 milliamps for a few minutes. Eventually, it settles down to the 35-40 range and that's where it stays.

2. The voltage reads 14+ volts when the truck is running, so the alternator seems to be working fine. Is there any chance a bad diode or something could be draining power that wouldn't show up in a parasitic drain test? If so, how would I diagnose that or eliminate it as a possibility?

3. Any other options on how to diagnose this without doing this test every night until I catch it?

Thanks for any input.