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BMW Intelligent Battery Sensor
Posted to Technical Tips Forum on 10/10/2017 8 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

Files Referenced:

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car Vehicle Data

2006 BMW 525i 3.0L

Engine3.0 L
Trans6-speed Automatic (Electronic)

car Vehicle Data

2006 BMW 525i 3.0L

Engine3.0 L
Trans6-speed Automatic (Electronic)