BMW Intelligent Battery Sensor
Posted to Technical Tips Forum on 10/10/2017
10 Replies
This E60 platform came in on the hook. The owner stated it
just wouldn't start in the morning after he shut it off
normally the night before....
Revision confirmed no start, no crank, no com on the
powertrain data bus. Cluster and driver information center
lit with quite a few warning lamps and messages.
[2006 BMW 525xi, Photo]
Power and grounds and can data lines were fine on all
participating modules on the bus.
On the other busses the EWS complained about missing wake up
signal and the safety&gateway module times out for a dsg
telegram.......
[2006 BMW 525xi, ECM/Inputs/Outputs Photo] [2006 BMW
525i, ECM/Inputs/Outputs Photo]
The different modules on the powertrain bus are woken up by
a designated " wake up" signal which should be sent to them
from the body controller once this controller detects
ignition switch in the run position. There are no discrete
igntion feeds (+15) to the pcm or so!
Tied into this wake up line bus is a so called intelligent
battery sensor (not really so smart). It is a mini module
that lives integrated within the negative battery terminal.
Its job is to inform about battery condition, discharge and
so on....It uses the wake up line to transmit periodically
its information. [2006 BMW 525xi, ECM/Inputs/Outputs
Photo]
[2006 BMW 525xi, ECM/Inputs/Outputs Photo] [2006 BMW
525xi, ECM/Inputs/Outputs Photo]
Once this little beast shorts out it will take down the
entire wake up circuit causing all the symptoms this BMW
exhibited when it arrived at my shop. The temporary solution
was just to disconnect the IBS from the rest of the wake-up
circuit until a new sensor is delivered. [2006 BMW 525xi,
ECM/Inputs/Outputs Photo]
This IBS is to be found on a LOT of BMW's as a quick search
revealed.Luckily this will be useful to somebody, someday,
somehow.
Jurgen from Mexico
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