Large parasitic draw on 12v system after windows left open in rain storm

[knightmb]

I don't think Leafspy used to work when the ignition was off. Is that correct?

Correct, when the Leaf goes to sleep, everything is shutoff, LeafSpy loses access, etc.

[coulomb]

By the way, here are the current DTCs read through LeafSpy:
... 6 scary sounding DTCs...

I'm guessing that some of those could be due to the auxiliary battery voltage having been very low, and your frequent disconnection of the negative battery terminal.

Perhaps reset the DTCs (if possible), and use a battery tender instead of disconnecting the auxiliary battery, and see which DTCs persist, Do this for one or two days. If you can't use the battery tender at work, postpone this to the weekend.

B29A0 296C charger N/CHG Port Engage Err VC- 95
B2802 2368 charger Q/CHG Isolation Sig Err VC- 56

I wonder with the Leaf's propensity to waste power checking the J1772 charge port, whether these faults might be the cause. Water has far more effect on high voltage than on low voltage, unless there is acid involved. Leakage from (e.g.) the quick charge (CHAdeMO) HV wires to chassis would explain the second error above ("isolation"). Perhaps try some moisture displacement spray around the CHAdeMO port and its wiring.

Though I would have thought that a HV isolation fault would be enough to stop the car from driving. Maybe it can know that it's exclusively CHAdeMO related, so these are allowable as long as you don't attempt a CHAdeMO charge.

[lorenfb]

By the way, here are the current DTCs read through LeafSpy:
... 6 scary sounding DTCs...

I'm guessing that some of those could be due to the auxiliary battery voltage having been very low, and your frequent disconnection of the negative battery terminal.

Perhaps reset the DTCs (if possible), and use a battery tender instead of disconnecting the auxiliary battery, and see which DTCs persist, Do this for one or two days. If you can't use the battery tender at work, postpone this to the weekend.

B29A0 296C charger N/CHG Port Engage Err VC- 95
B2802 2368 charger Q/CHG Isolation Sig Err VC- 56

I wonder with the Leaf's propensity to waste power checking the J1772 charge port, whether these faults might be the cause. Water has far more effect on high voltage than on low voltage, unless there is acid involved. Leakage from (e.g.) the quick charge (CHAdeMO) HV wires to chassis would explain the second error above ("isolation"). Perhaps try some moisture displacement spray around the CHAdeMO port and its wiring.

Though I would have thought that a HV isolation fault would be enough to stop the car from driving. Maybe it can know that it's exclusively CHAdeMO related, so these are allowable as long as you don't attempt a CHAdeMO charge.

Yes, as it relates to extraneous current. The key issue with water is the circuit board corrosion and damaged circuit tracks.
Even more problematic is the moisture entering ICs and damaging the IC chips. Seriously doubt that Nissan specs Hi-Rel
military grade IC packaging (ceramic) for its ECUs. Water damaging ECUs is very common on many ICEVs, e.g. Audi, Porsche, BMW.
Water always finds a way in!

[Stanton]

I don't think Leafspy used to work when the ignition was off. Is that correct?

I believe that's a fact, so you may be on to something.

[LeftieBiker]

When you plug the dongle in with the car off, there is some activity, according to the lights on mine.

[GerryAZ]

There are some terminals of the OBDII port that are powered without the car being on, but LEAF Spy needs the CAN Bus communication to be active so it can read data from the various control modules. Therefore, the car must be on to get reliable information from LEAF Spy.

Enough systems will power up briefly when a door is open to allow LEAF Spy to connect, but the connection will drop as soon as some modules go to sleep when there is no activity. Even when LEAF Spy is connected without the car being on (when opening a door, for example), it does not display complete and accurate information because it cannot get data from modules that are not communicating.

The M/C relay (and perhaps the SSOFF relay) being energized is keeping the various modules powered which causes the excess current draw. You unplugged the window switches, but what about the other switches in the doors? Also, the keyless entry system has circuits in both front doors and the hatch that are active all the time. Those circuits might keep the VCM from sleeping and shutting down the relays.

[Dovetail]

The M/C relay (and perhaps the SSOFF relay) being energized is keeping the various modules powered which causes the excess current draw. You unplugged the window switches, but what about the other switches in the doors? Also, the keyless entry system has circuits in both front doors and the hatch that are active all the time. Those circuits might keep the VCM from sleeping and shutting down the relays.

I will give it a more thorough attempt. This weekend I will unplug all those switches again, and maybe even the parking brake and gear shift buttons (this was quite a violent rain storm- both seats and center consol were wet) to be sure.

Last night I put in a good 40 Ah SLA backup battery that I had, and cleared all the codes. I will take coulomb's reccomendation and keep it hooked up for a couple of days using a battery tender and see what happens. I also unplugged the 2G TCU for good measure since I was already under the dash and it is certainly not doing anything useful.

If these tests fail, would it be useful to monitor the CAN Bus messages? If so, can anyone point me towards a reasonable DIY way to read them? I haven't done my research on this yet. I'm guessing I would need a dealership to use their scan tool on it.

[Dovetail]

Two full days of a good battery, and disconnecting every plug in the doors and center console didn't result in any changes. I'm out of ideas at this point (Other than hooking a toggle switch up to the SSOFF relay to easily shut it down). I did purchase a salvage BCM for $75 on ebay. It seems like the most likely of the modules to fail. I hate throwing parts at a problem without knowing it is the problem, but we will see what happens when it arrives.

[knightmb]

Two full days of a good battery, and disconnecting every plug in the doors and center console didn't result in any changes. I'm out of ideas at this point (Other than hooking a toggle switch up to the SSOFF relay to easily shut it down). I did purchase a salvage BCM for $75 on ebay. It seems like the most likely of the modules to fail. I hate throwing parts at a problem without knowing it is the problem, but we will see what happens when it arrives.

Well, the only thing I would suggest is to start looking for simple issues. Maybe none of the modules or electronics is the issue. It might be some sort of short somewhere in the wiring between the positive and negative. Since the power draw is low, it's not enough to melt the wires but enough to be annoying.

[Dovetail]

Well, there is good news and bad news.

The used BCM arrived yesterday. I installed it this evening, and the car seems to go to sleep properly. The current is around 250 mA after a few minutes. The bad news is that I didn't realize that the key is programmed into the BCM, so it doesn't actually start up for a proper test. It just gives me the key is not detected symbol. I also didn't close the windows before swapping it, so it looks like I have to put the old one back in to get those windows up while I figure out how to program my key into the new BCM.

I think that's progress though!