austingtir

car is dead no lights usually when you reconnect the battery because the boot is open the boot interior lights come on this was the initial give away to me that something wasnt right.

Is there any fuses I can check iv had a look through the online fuse diagrams cant see much relating to the battery control module other than whats right next to the battery that seems to be ok.


All I have done here is move the battery from the front position to the side position of the boot to allow room for the compact spare wheel to fit in there.....

So that entails moving the battery control module too which is a simple job of just relocating the harness and the battery and drililng through the plastic and re mounting the battery securely in its new position. Only bit where I got a bit rough was it was pushing/reshaping the thick + battery cable to it would meet with the battery terminal in a nice manner and not push on them to much.....


Im really surprised by this... Looks like iv got an expensive bill for a battery control module coming up??

I opened the lid on the battery control box and nothing is burnt inside has anyone pulled the circuit board inside out?? Im assuming its just controlling a big relay to latch and unlatch the ground?

austingtir

Ok I got the dual battery system manual for the w211.

Looks like I need to check fuse box f32 in the front passenger footwell tomorrow and go over the big 200 and 150 amp fuses in f33 again to make sure none of them are burnt.

coupesedan

reversed the terminals for a couple seconds? lol

austingtir

No deff not.

Its really simple theres no way I put the terminals the wrong way around. The positive terminal on the battery was always closest to the + battery terminal theres just no way I did that.

Thats what I dont get about this.

My gut feel is I just disturbed the battery control module (or the wiring) and its finally decided to chit itself.... seems weird though for it to just go like that.

usually when you connect the negative you get noticeable sparks of it drawing current and then the interior boot lights light up. Now it does really tiny sparks and nothing happens really noticeable difference there.

machild

Continuity testing will tell you the problem.

austingtir

No resistance through the BCM - battery negative terminal to ground which means its not cutting off the connection to the battery.

No resistance through any of the fuses in the back tire well. My car is RHD so im just trying to remove the carpet on the drivers side of course the seat is just forward enough to stop me lifting the carpet easily...... FFS.

So checked all the main fuses in f33 and f32

There is no power with the battery connected to the F32 fuse box.... Im getting 2.3volts from the main battery line to the f32 fuse box.....

austingtir

Ok got it.


It was my ground I tried to ground it to the bumper bar bolts and it decided that wasnt good enough.

Moral of the story is use the factory ground points!!!! And check the easiest stuff first (which I thought I had).