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  #11  
Old 01-16-2017, 09:38 AM
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Quote:
Symptoms are:
  • the hazards will come on....
  • followed very shortly after by the interior lights coming on
  • and very very occasionally the doors unlocking
Considering that you have a code that says that the crash sensor has been activated...the 3 things listed in your quote happen to be the things the car will do automatically when a crash has been detected...the hazards turn on, the car doors unlock, and the interior lights turn on. Thus, it could be presumed that your crash sensor is defective (or has been "activated").

The crash control unit (CCU) used to be a stand alone component...with crash sensors (usually bright orange in color) located around the car (back in the day).

But BMW changed things electronically in 1995 & combined the function of the CCU into the Light Module (LM)...and this continued with the next iterations of the LCM (lamp check module) that combined the check control module into this one component.

The crash sensors were replaced with impact sensors & communication from MRS (multiple restraint system) sensors to the LCM in the event of an accident.

If the battery voltage can be ruled out as the culprit...then looking into why the crash sensor has been activated would be a direction I'd look. Was the vehicle in an accident or is the LCM defective?






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Last edited by Qsilver7; 01-16-2017 at 09:51 AM.
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  #12  
Old 01-16-2017, 09:56 AM
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Originally Posted by Qsilver7 View Post

The crash sensors were replaced with other types of sensors (acceleration/deceleration) sensors.

If the battery voltage can be ruled out as the culprit...then looking into why the crash sensor has been activated would be a direction I'd look. Was the vehicle in an accident or is the LCM defective?
Completely agree that something is activating the crash program..hence the fault code. It hasn't been in a crash but just thinks it has!

However if the LCM was at fault surely the Crash Sensor Activation fault wouldn't show in the ZKE module because it's this module tells the LCM (via the IKE) to activate the 'crash mode'. If the LCM was defective and decides to just randomly activate the 'crash program' lighting then surely it can't then send that message back to the ZKE as according to the diagrams its a one way message path.

So presumably once voltage has been ruled out then the fault either lies in one the acceleration/deceleration sensors or the ZKE module itself, or perhaps the IKE module too?

Would you happen to have a diagram to show the exact path of how the signal from the crash sensors ends up at the LCM?

Last edited by V8 00USH; 01-16-2017 at 10:08 AM.
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  #13  
Old 01-16-2017, 10:03 AM
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Drove home and parked up on the drive, walked in and got a shower. Came out the shower 10 mins later walked downstairs and could see the hazards flashing through the window!! FAILURE....
Oh my bad, I guess the hazard lights coming on after you came out of the shower was with the key on but only after you replaced the ballasts!
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  #14  
Old 01-16-2017, 10:10 AM
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Originally Posted by 80stech View Post
Oh my bad, I guess the hazard lights coming on after you came out of the shower was with the key on but only after you replaced the ballasts!
You're kidding me....right?
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  #15  
Old 01-16-2017, 10:10 AM
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My take on the car's communication bus is that a crash would initiate MRS...then it would send a signal to the LCM, which then would initiative the interior lights, hazards, and also send a signal to the GM to unlock the doors.

The IKE is involved because it is the MAIN gate keeper of the vehicle's communication bus. It doesn't necessarily "control" things...but rather is a gatekeeper and passes data to/from just about every module as data is transmitted and received to/from the various modules that requires the specific data:

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  #16  
Old 01-16-2017, 10:17 AM
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Originally Posted by Qsilver7 View Post
My take on the car's communication bus is that a crash would initiate MRS...then it would send a signal to the LCM, which then would initiative the interior lights, hazards, and also send a signal to the GM to unlock the doors.
So how does the MRS system talk to the ZKE module then? Directly or via something else? If the MRS was being initiated then I wonder why my air bags aren't going off right, left and centre too!?
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  #17  
Old 01-16-2017, 10:18 AM
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Hi V8,

I hope you are able to solve your flashing light mystery soon but this is how I fitted a battery maintainer into my X using the battery access points in the engine bay.

It keeps my now, 9 year old OEM battery topped off nicely. No, I wash't the one who purchased a BMW battery and am planning any month now to put an AGM technology battery in it.



The "E" connection goes to an engine oil pan silicone heating pad and the "T" goes to a transmission pan heating pad for deep freeze operations in Wisconsin.

I have one of these little SE1-125-CA Schumacher maintainers fitted to all my vehicles and standby power equipment (riding mower, generator, etc.) and they do a great job of keeping my batteries at the ready.

Mike
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  #18  
Old 01-16-2017, 10:22 AM
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Originally Posted by semcoinc View Post
I hope you are able to solve your flashing light mystery soon but this is how I fitted a battery maintainer into my X using the battery access points in the engine bay.

It keeps my now, 9 year old OEM battery topped off nicely. No, I wash't the one who purchased a BMW battery and am planning any month now to put an AGM technology battery in it.
Hi Mike

Me too....it's driving me insane and stopping me from enjoying the car or wanting to leave it anywhere. I'll let you know how I find the AGM battery but from what I've read I really can't see any downsides.

I've got a couple of other things to setup at my house to finish off the 'battery maintainer' project so I'll keep people posted.

The Ctek charger I use has also got an AGM mode on it too which will be useful for when I charge it.
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  #19  
Old 01-16-2017, 10:33 AM
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Hi V8,

Yes, , the AGM technology appears to be a very good move in batteries. I'm looking forward to getting one in my X when I see a good sale price offering.

Mike
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  #20  
Old 01-16-2017, 11:03 AM
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Originally Posted by V8 00USH View Post
So how does the MRS system talk to the ZKE module then? Directly or via something else? If the MRS was being initiated then I wonder why my air bags aren't going off right, left and centre too!?
Seems that the ZKE (GM) module sends signal to the LCM and not directly from the MRS



Next step I think is to scan the MRS module and see if there's been a crash detection error code. I presume it would store one. If there hasn't then you would then perhaps think that it's the ZKE module at fault perhaps or that somehow it's getting a rogue signal? If I knew which wire the signal came down from the MRS module to the GM module I could perhaps snip it or unpin it from either end temporarily to see what happened.
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