The car is a 2003 e55

I purchased it in Japan. Very good condition, low km and it shows. BUT I have had it for a month and it has been a month of trying to sort through the bouquet of electrical problems it has thrown me, along with some bad luck/stupidity

When the car arrived it was Jump started, possibly multiple times on the way over the ocean. That I am guessing is problem #1.

Initially it gave me a barrage of codes and messages, which I have cleared off with icarsoft 980, and various reset procedures. 31 of 47 systems had DTCs stored and current.

At this point I have replaced both batteries. Which has solved a few more codes including weirdly enough evap system DTCs.

BUT the following are the problems that persist to one extent or the other and this is becoming extremely frustrating.

1) After the main battery was changed:
a) head unit (Command I guess) will not turn on. Cd changer, display: no signs of life. Fuse 6 (40a) in the Rear Sam was fried. When I replaced it, nothing changed. Is there another fuse for the he command or the display?
b) the only way I can open the trunk is with a physical key, which is a massive PITA. Did I trigger a valet mode? Is it somehow related to the fries fuse? The trunk pop button on the door lights up.

2) yesterday got the dreaded SBC message and breaks went out on me. This also happened before I replaced the batteries and that seemed to have solved it. (Or so I thought)
Code shown C26FB. A7/3n1 SBC internal fault.
Before battery replacement it was accompanied by DTCs for consumer battery shutoff 1 and 2 for undervoltage, a bunch of other messages and preceeded by convenience features disabled message.

3)I measured main battery voltage and overnight it drops pretty significantly.
-When I shut off reads 12.8 or so.
-when I come back the next day could be 12.4 to lowest 11.8! when the car sat longer.
- when running, shows 13.9-14.1 so alternator is charging.
-again all batteries are brand new.

I tried measuring current draw but getting 0 from multimeter. Icarsoft scanner when I check BCM status on shut off locked vehicle even after 5 min shows -2.4A for a brief few seconds then 0. Not sure if this means anything or this is just the draw from the scanner itself. (Seems like a lot)


I cannot help but feel like this is all connected.

Is the rear SAM fried and drawing current?
Battery control module?
Voltage reg? Ive seen it suggested but I don’t think it is.
What could the trunk issue be? Related or separate coincidence.


Any input would be greatly appreciated. I know these are common issues unfortunately on w211s. Makes me really regret getting this car at this point. 😩

I am dreading having to take it to a local dealer as I have had negative experience with them before and I know of no good local indies to entrust this problem to.

Thanks in advance

 

As a possible reason for trunk lock not working, remove left side trunk liner and hinge cover and look for any broken wires that are in the harness, at the end of the hinge.