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

[Dovetail]

Hi Everyone,

I have thoroughly enjoyed my 2012 leaf for the past 6 months. I was just thinking how little work I have had to do on it, when an unpredicted isolated thunderstorm dumped 1/2" of rain through the open front windows. When I got home, I turned it on and rolled up the windows with no trouble. The next day at work, I let it dry out in the sun with the windows open. When I came out at the end of the day I was greeted with a dead 12v battery. It started right up with a jump start and I drove home thinking nothing more of it. LeafSpy showed it charging the 12v battery properly. The next morning, dead 12v battery again. I checked the current draw with a clamp on ammeter at the negative battery terminal with the car off, doors closed and after waiting 10 minutes. It shows just under 3 amps of draw with everything off. This kills the 12v battery very quickly...

So far I have tried pulling fuses one at a time while checking the current draw at the battery. All test were done with the car off, and driver door open, but pillar switch pushed in. When I pulled fuse G,H,I from Fuse Box #2, the draw drops to about 1 amp. If I pull fuse #43 out of Fuse Box #1, it drops to about 0.1 amp. I also noticed that the M/C relay in the Relay Box is warm to the touch and seems to be active (clicks on when I place it in its socket. The same is true of the motor fan relay in fuse box #3.

Other than that, I unplugged both front window switch pods as recommended in another post (they both certainly took on water), with no change. I also removed the glovebox to look at the VCM since both relevant fuses seem to relate to it. It looks dry, and can't imagine it getting wet from that rain storm so far under the dash.

Does anyone have any thoughts? I am about ready to just install a disconnect on the negative cable and disconnect the battery whenever I park for more than a couple of hours.

[Stanton]

Not to state the obvious, but what makes you so sure that your 12v battery isn't "shot" and needs replacement? Once you "kill" a lead-acid, it doesn't necessarily bounce back. I don't know why some of the relays should be "warm to the touch" after disconnect/connect, but water can do strange things to electronics.

[Dovetail]

I guess I am not sure. It holds its voltage well overnight after charging and dissconnecting it from the car, but I'm sure it will be shot after this treatment even if it is not already. If the battery is no good, what would cause the car to draw current from it when it is turned off? If some of the electronics sense a low voltage do they not shut off for some reason?

I will try a known good battery and see what happens. That is certainly an easy test.

[Dovetail]

I tried another battery that I know is good, but still the same results. I made sure it was topped off with a separate charger first before installing it. After about 15 mintes with the car off and without disturbing any doors/windows, it was reading a voltage of 12.5 and a current draw of 2.24 amps. Any other ideas?

[goldbrick]

You can probably find a wiring diagram for your Leaf at nicoclub.com. I'd look through that and see what circuits are powered by the fuses and/or warm relay you mentioned in the OP and try to determine if they are malfunctioning somehow.

[knightmb]

I tried another battery that I know is good, but still the same results. I made sure it was topped off with a separate charger first before installing it. After about 15 mintes with the car off and without disturbing any doors/windows, it was reading a voltage of 12.5 and a current draw of 2.24 amps. Any other ideas?

That 28 watt power draw would kill any Leaf SLA after +13 hours of use given the SLA was brand new, fully charged when you started. I'm guessing that either you drive the Leaf often enough to not encounter a dead 12V battery or the mystery load must be stopping at some point?

[Dovetail]

That 28 watt power draw would kill any Leaf SLA after +13 hours of use given the SLA was brand new, fully charged when you started. I'm guessing that either you drive the Leaf often enough to not encounter a dead 12V battery or the mystery load must be stopping at some point?

At this point, I have to pull off the negative terminal if I am parking for more than a few hours, otherwise it will be flat at the end of the work day.

I have the factory service manual and have been looking through the wiring diagrams. One relay is the SSOFF (VCM Self Shutoff) relay. Its signal comes from the VCM, and its purpose is to turn off the VCM. Its switched line goes right back to the VCM. From the FSM-"VCM also activates the SSOFF relay so that it can shutoff VCM power when VCM stops (self shutoff)."

The second one is the M/C relay, which recieves its signal from the VCM, and is responsible for supplying power to each ECU in the VC system. So it seems that something is keeping the system from turning off. I don't know if that is a faulty sensor or switch that may have gotten damaged fromt the rain, of if that was just a coincidence.

I guess the next thing i can do is bench test the two relays, but after that I am not sure where to go.

[lorenfb]

That 28 watt power draw would kill any Leaf SLA after +13 hours of use given the SLA was brand new, fully charged when you started. I'm guessing that either you drive the Leaf often enough to not encounter a dead 12V battery or the mystery load must be stopping at some point?

At this point, I have to pull off the negative terminal if I am parking for more than a few hours, otherwise it will be flat at the end of the work day.

I have the factory service manual and have been looking through the wiring diagrams. One relay is the SSOFF (VCM Self Shutoff) relay. Its signal comes from the VCM, and its purpose is to turn off the VCM. Its switched line goes right back to the VCM. From the FSM-"VCM also activates the SSOFF relay so that it can shutoff VCM power when VCM stops (self shutoff)."

The second one is the M/C relay, which recieves its signal from the VCM, and is responsible for supplying power to each ECU in the VC system. So it seems that something is keeping the system from turning off. I don't know if that is a faulty sensor or switch that may have gotten damaged fromt the rain, of if that was just a coincidence.

I guess the next thing i can do is bench test the two relays, but after that I am not sure where to go.

Hopefully, it's not an ECU that got water damaged. It's not uncommon to have that occur on any vehicle whether a BEV
or an ICEV, after a very rainy season where a water ingress occurs. A water damaged ECU is typically not repairable,
and ECUs can be very costly.

[Dovetail]

Well I bench tested the two relays this evening, and both seem completely fine. Another thing I noticed is that when I plug in the bluetooth OBD adapter, LeafSpy is active no matter what the state of the car's ignition is. I guess that makes sense if all the varius ECUs are not shutting off. I don't think Leafspy used to work when the ignition was off. Is that correct?

[Dovetail]

By the way, here are the current DTCs read through LeafSpy:

C1A62 0108 BRAKE Control Mod Pwr Supply BR-53
B29A0 296C CHARGER N/CHG Port Engage Err VC- 95
B2802 2368 CHARGER Q/CHG Isolation Sig Err VC- 56
B2821 2328 CHARGER 12V Power Supply VC-65
U100A 876C CHARGER
B2902 4268 CHARGER OBC Memory Error VC-91