bernard farquar

I wanted to start a new thread, because there are many drain threads, and they have many people chiming in with "me too" and I didn't want to hijack someone elses thread.

I have been having a battery drain issue for some time. I have removed the batteries, charged them out of the car, and left them for multiple days to verify they don't have internal issues. (no voltage drop unhooked)

I am reading around 1.4-1.6 amp draw on my meter, bridged between the ground lead and negative post of the battery. I am waiting six minutes before getting a reading, with the trunk open but the latch snapped closed.

I tried unhooking the seat module, still drained. I tried pulling the stereo fuses, still drained. I finally pulled out ALL the fuses from the passenger compartment fuse panel, along with the #6 fuse from the trunk (just because I don't trust the audio gateway) and the reading dropped down to .01 on the high amp reading. (close enough for diagnostic) I start putting in fuses and the one that seems to be the culprit is the #40, listed as "switch off relay" because with all but that fuse in, my draw is below 1 amp (I was unable to wait the six minutes for everything to go back to sleep because as I was awaiting the final reading, the SBC pump cycled and smoked the fuse in my meter)

What the heck is the switch off relay, and more importantly for my purposes, where?

Special thanks to Konigstiger for posting the procedure in another thread that walked me through the diag.

MBENZTECH

Fuse #4 on which fuse box??? Front, rear or inside vehicle.

konigstiger

F40 is UCP @ interior fuse panel.

bernard farquar

HA! it's listed twice on my fuse table, so I quit looking once I found one answer.

bernard farquar

That information is literally listed in the owner's manual, there is only one #4, although I actually referenced #40 . Not sure what you're attempting to add to the conversation.

bernard farquar

Quick update. After one night sitting with everything hooked up bit the #40 fuse, battery seemed to stay fully charged and started right up. ESC shows inoperable at start up, but probably because the ESC button is on the affected panel. Fingers crossed I have found my drain and can reassemble and start driving my car again.

bernard farquar

Has anyone replaced this switch with a used one that had more features? I'm wondering if one of the many I see on ebay which have heated seat switches (mine doesn't) would work for me, just having a switch that doesn't do anything, or is the whole connection different, rendering a slightly different switch useless for me?

I guess I can throw 25 dollars at one to find out, but would prefer to use someone else's time and experience to find out.

ratfancy

OK -so I had to jump my car one day. Got a new battery (after only 2 1/2 years, still had a full warranty). My husband thinks there is a parasitic drain. I took it to my shop, they tested on two different meters, and waited 30 minutes and tested again, and found no problem. However, my husband checks the battery charge every day, and after short trips it settles on 71% charge. Is this normal for my 2011 E350?

bernard farquar

What is 71% charge as described in a voltage reading?

ratfancy

Sorry I jump around to another thread. See https://mbworld.org/forums/e-class-w...ml#post7640763

bernard farquar

So my battery charge level seems to be staying at 12.4 volts, which I read as slightly discharged, but I have read other threads stating that this is normal? I don't seem to have the drain anymore, so I guess I can reassemble my trunk floor and move on to the switch replacement. Haven't been able to find any threads on anyone using a switch with more features than the original one either successfully or unsuccessfully. I seem to be able to find lots of switches available from cars that had seat warmers (I don't) for fairly cheap, maybe I will just spend 30 bucks and find out if it matters.