So - I finally got my hands on a data logging multimeter and decided to try and track this down once and for all on my rig. The issue in my case was the rear DVD player intermittently spinning up. I ran many data log sessions and identified some clear patterns of what normal/abnormal draw levels are and how they look over time when graphed. After reproducing the issue on multiple occasions I was able to confirm that the rear DVD player (passenger side third row) was lit and could hear it spinning up when I saw the draw.
In order to reproduce the issue but still have access to the fuses in the engine bay and junction boxes by driver and passenger sides, I latched the hood and also clamped the door sensors. I used voltage drop testing to confirm the 30ABat fuse, and then downstream it was the 10A radio fuse. From there there were only a few options off the 10A radio fuse, but once i saw
this thread and the reference to the 7.5A fuse under/behind the glove box it was easy enough to isolate the DVD as the culprit by pulling the 7.5A fuse and confirming. I am going to do more testing over a period of a few days after the holidays, and will provide some followup on this thread, but I was able to identify some clear patterns of normal and abnormal draw behavior under various conditions and this looks pretty clear.
I should mention that I had the car at the dealership a few months ago to try and resolve the issue, they had the master tech looking at it, they had me replace the driver side kickpanel junction box for a total of $2k (they acknowledged they couldn't be sure whether it would fix or not). To my dismay it didn't fix the issue, as the car had died again multiple times even after a new battery - they thought it was . I got sick of this and with some time off around the holidays decided to track it down once and for all. Also confirmed no short or grounding issues and no issue w battery terminals.
A couple of approaches/tools that ended up being indispensable:
1)
IH8MUD - the community of knowledgeable dedicated owners/enthusiasts is an amazing resource
2)
Voltage Drop Test - the old school approach of pulling fuses is probably fine for situations that are consistently drawing current like a short or stuck relay, but if it's intermittent and related to a computer system you need the car to go to sleep. Without using this approach, pulling fuses means you're starting from scratch each time you pull one. I believe an issue I had in previous attempts at using this approach was that earlier meters I used were not sensitive enough to give accurate mV readings, and I didn't appreciate that when measuring the mV the numbers jump initially before they settle so it looks strange to the untrained eye, like it's unreliable.
3) realizing that
even the hood latch need to be closed (used a screwdriver) in order to get the system to behave normally and go to sleep.
4)
data logging multimeter (strong preference for Fluke's Trendcapture capability on the 289/287 series) - this made it easy to log data over time and identify patterns - what's normal or not. When using conventional data logging capability you can quickly get into large amounts of data that can make it hard to see the pattern and you waste a lot of time sifting through the data points (all the data logs meters I used were crazy slow so it could take 20+ minutes to transfer a session of 10k data points. With Fluke's trendcapture it really was amazing once I got comfortable with how it works and the settings, b/c instead of logging intervals of 1, 2, 5 seconds I could now use 1 minute or longer intervals, but set 'events' to trigger if the meter value changes more than say 10% of previous stable reading and it will then log those events. Furthermore, I could view the graph immediately to see the pattern rather than having to transfer the data each time. Also - fluke system allows you to track multiple sessions on the meter, and easily track them as separate sessions with associated settings and timestamps so you can easily keep track of what's what.
5) Priority Start deserves credit as well b/c it hasn’t been a showstopper for me over the past 7+ years, just a nagging nuisance in the back of my mind. But was never stranded on account of this issue.
6)
top post blade style disconnect switch. Made it easy to disconnect when needed and more important made it easy to Test draw without interrupting things.
Thermal imaging was a dud for me for this use case. I tried very high quality (320x240) thermal imaging and it just didn't seem precise enough with enough resolution to show me the fuses or wires that were active. I liked the form factor of the Extech 540 but can't recommend it for the datalogging capability (or could recommend with some serious caveats), the fluke 28x series was insanely helpful for this - turned it into an almost trivial exercise to capture and analyze the data and easily keep track of it. The flukeview forms was pita and felt like it was industrial software from the 90s (probably is), but it still made it easy (once getting used to the software) to analyze the data across multiple sessions and annotate it to keep track of different sessions easily.
