eugenek

I have a Lexus RX 350 2010. A few months ago my car didn't start after a cold night. Battery was only 2 years old from Costco but it was dead. I though about faulty battery and went to Costco and changed it for a new one. After about a month I had to leave for a week but when I came back the battery was dead again.

I started troubleshooting the issue and that's what I figured out so far for the car with switched off ignition:

Measuring power draw using multi-meter shows there is cyclical parasitic power drain of about 0.8-0.6 amp every 5-6 secs then it drops to 0.02-0.03 level for couple of seconds and then it spikes back to 0.8-0.6. This cycle continues forever. I connected Techstream software and even though it doesn't show any errors the diagnostic tool in navigation window shows error code B15C3 which is "Speaker output short". According to the manual it could be either short in speakers or amplifier issue.

So, I disconnected amplifier. The cyclical power drain was still there. I removed fuses related to amp and audio. The issues was still there. I tried to measure voltage drop on EVERY(!) fuse in both boxes(inside and under-hood) but it didn't show any.

I resorted to drastic measures: I removed ALL(!!!) fuses from two boxes: inside and under-hood. The only fuses I couldn't remove was high amp cartridge fuses in under hood fuse box.
So, I am standing and looking at the car with disconnected amp, all fuses removed, all wires in under hood fuses box removed but my multi-meter STILL SHOWS CYCLICAL BATTERY DRAIN.

I am out of ideas at the moment. Do you guys have any suggestions?

ZeRoSL

I'm also having this issue on my 2010 RX350.
I am resorting to wire in a solar charger to counter the parasitic draw

Droid13

Maybe something snacking on the wires. Since the only clue you have is the speaker short, why not follow the diagnostics procedure and test all the speaker wiring for shorts. It seems that removing the fuses would solve that, but maybe those wires are in the area of other affected wiring and get your closer.

heshamos

Wow, this is mind boggling!

Let's start with how do you measure the DC current draw?
How long have you tested the draw for?

N4TECguy

Are your keys too near the car and causing it to "stay awake"?