The car is 2004 S80 with less than 50K miles that my sister inherited and promptly trashed. She also does not drive every day. A few months back the DIM and CCM went dark, no power seats etc. VIDA/DICE couldn't see anything to diagnose.

When using the internet to solve tricky car problems I always keep in mind "if you hear hoofbeats think horses not zebras", as the typical problems never get written up, so if you suspect something simple, make sure that is not the problem. In any event, There were lots of writeups about bad solder joints on DIM circuit cards and possibly the CCM console. I pulled the DIM and it looked quite different (later generation) than the ones that had the problems, and abandoned the effort to take it apart and continued reading. Turns out it was poor constant 12v supply to the relay from fuse 24. I jumped it, put the DIM back in and evertyhing lit up and worked, the only remnant was the SRS warning that I hadn't gotten around to reseting with vida/dice. That was, until the battery started dying.

New battery later, intermittent drain became more constant. 5amps with everything shut off.

From the forum here I got three useful pieces of advice, first rule out the alternator diode (horse hoof beat). Second wait for the timer to expire (courtesy lights go out) after latching the doors/trunk/hood latches to make the computers think the car is shut up so it will turn off things in a minute or two. Third, how to measure indirect load by measuring the millivolt drop across the fuse using the chart found at https://www.powerprobe.com/s/Fuse_Voltage_Drop_Chart_-_Standard_Fuse.pdf as well as directly with an ammeter in series between the battery post and cable.

Once I got the hang of it I pretty quickly determined the load was coming from fuse 24. I swapped the relay around (couldn't have been that simple a fix) and was mulling around a solution like a cut off switch (sister would likely not remember to switch it off) a dead man switch on her key lanyard (not something you find in your local auto parts store) or wiring up some kind of relay. I was talking with a friend about how I was going to draw power and put in a switch at the fuse when we came up with a very elegant solution that required two wire jumpers and a couple of blade taps.

Fuse 24 is constant 12v bus. The car had fuses in the positions for the heated seats (the one feature the car does not have, this is florida after all) which are switched to the ignition. Bingo.

I put a blade tap on on the constant 12v pin of the relay and ran a wire from it to the fuse box. Then I took the fuse out of position 24 and put it in place of the 15 amp fuse in the heated seat position (fuse 24 is 10 amp). I put another blade tap on the load side of the seat heater fuse and connected a wire to it. Now I took both of these wires and another blade tap and connected both wires to the load side of fuse 24 with no fuse inserted.

No permanent changes to the car wiring so if I ever get around to finding what is drawing the extra load, I can pull the jumper from the seat heater and put the fuse back in. Any other wires (beside the one to the relay) from fuse position 24 are still energized even though the fuse is out.

So now everything that was constant 12v from fuse 24 is now switched to the ignition. Hooked the battery back up and everything worked. Disconnected the battery and put the ammeter back in series and waited till the courtesy lights etc timed out and bingo, one tenth of an amp current draw. Reconnected the little harborfreight solar cell in rear window via the over voltage cut out controller and with a little luck I should be done jump starting her car.

Hopefully this is not hubris...

 

The problem with long posts is that no one reads them.

Maybe you need to shorten the post and come to the point as to what you need. Lots of people here will help you. I stopped after reading about your sister trashing the car.

 

your loss. I wasn't asking for help, I was sharing a solution with others

I read dozens of posts and followed long threads on this subject that went nowhere. Bottom line is this is a solution to a phantom current drain common to a lot of these cars.