Hello all. I have done as much leg work as I know how to do, and I’m hoping the car enthusiasts on here can help me continue on. My car is a 2008 TL Type S. I love the car. I have had it for almost 2 years and it is my daily/commuter car. However, since I’ve had it, if it sits for more than a few days or so, the battery will be dead. Parasitic draw issue? Easy enough, right? So here’s where I’m at with it…

I disconnected the stereo system, which had zero effect on the draw. The HFL has been removed since before I got the car. The AC relay had no effect on the draw.

The draw measures at 150ma ish.

I pulled fuses under hood one by one. The only one that made a difference was #15, which dropped the draw all the way to zero. Then I started pulling fuses connected to #15 under hood and here is what I’ve found.

Under hood fuse # 7 has 6.5ma draw
in cabin fuse #5 has 30ma draw
in cabin fuse #6 has 2.4ma draw
in cabin fuse #7 has 113.5ma draw
in cabin fuse #8 has 0 draw
in cabin fuse #9 has 0 draw

so it seems to me, if I could get in cabin fuse #7 to stop drawing power, that should solve my issue as I will then be under 50ma parasitic draw. Obviously I’d like to be lower if possible, but that would be a great start.

This photo I have attached shows the circuit for fuse #7. What would be the most suspicious component I should check and how do I do that to verify it’s the problem here? I guess unplug the component? There’s not a whole lot on #7 so I’m surprised it’s drawing so much power.

Any help appreciated!

 

Window master switch would be a culprit to me.

 

Oh shoot, apparently I missed the light white wire on the diagram that leads to a bunch of other stuff. So now I guess out of everything #7 feeds, what’s the usual suspects for parasitic draws?

 

Did you ever figure out the issue? I'm having a very similar problem, drawing 300+ milliamps until I unplug the driver side window master switch, then it drops to normal levels. Tried buying a used one (not inclined to drop $350 on a new one for a car I plan on selling), but had the same issue. Could be another faulty master switch, but I'm curious if there is something downline from that which could be causing the drain. I unplugged with window motor to check, but no affect.

 

I did! My issue wound up being an iPod adapter that had replaced the XM module. Apparently that circuit is well known for going bad whether it’s the xm module or something that replaced it.

 

Glad you sorted it out! I think I have it nailed down to the master window switch, but have a few more tests to try to isolate it. Of course I blew the fuse in my multimeter, so now I'm on hold till those get here haha!