Hi everyone. My 2009 G37 has a parasitic battery drain. In the cold winter, the battery would drain after not using the car for 1 week or so. I replaced the vent control valve at the dealership and the car held its battery charge for at least a week (until I could use the car again).

Now, even with a new battery, the car doesn't hold a charge for more than a day or two. I brought the car into a mechanic and they found the ABS motor pack circuit was drawing 750mA. Since it's a triple breaker, they cut the wire for the circuit that only servers the ABS motor pack, and they said it now drains only 160mA. But the car still doesn't keep a charge for more than a few days! Even after I plug a trickle charger into the car, the battery drops below 8V, and the key fob receiver won't even work!

Is this car kaput?

 

When I had that issue, a bad battery would keep the trickle charger from doing anything.

But you need to find out why the ABS is staying active with the car off. There's a bunch of small parasites (NAV for example, and security) but the brakes shouldn't be ABSing when off.

 

Thanks for the reply! The ABS circuit was cut, so it can't be drawing power. Also this power draw making my car useless after 2 days (instead of 7 days after replacing the VCV) seems to have started after I drove over a big snowbank, and the bottom plastic tray came off. Is it possible that water got into an electrical harness? How can more than 1 circuit be drawing so much power to completely drain the battery in 2 days?

The trickle charger is working fine for me, after plugging in a 10A charger for a day the battery reads over 12V. I would never have thought a bad battery could prevent a trickle charger from working!

 

Learned that one from experience - had an Optima Red-Top go tango uniform and the trickle charger would just throw an error after trying for about 30 minutes.

Parasitic drains are, as you've noted, hard to chase down. I'd put a current meter between the battery negative terminal and the wire harness terminal, and then start removing fuses one at a time to see where it is (could be multiple things if you've got a wet/compromised wire harness). It's painstaking work.

 

Did you change your radio out or add ambient lighting or something? Is car 100% stock?

 

If there's a wet/compromised wire harness, what could the repair be? Is the purpose of identifying the circuits in a wet/compromised wire harness to know which wires would need to be replaced?

Car is 100% stock, no car starter, OEM radio.

Forgot to mention, the airbag light is also on with the passenger occupancy sensor failure code, though this might be unrelated.