No Communication to Dynamic Stability Control module on BMW F-Chassis vehicles 5 Series, 6 Series

Joshua Technical Support Specialist Commack, New York Posted  
Resource
Electrical
2012 BMW 750Li 4.4L (N63B44A) 6-spd (A6HP26Z)
Dynamic Stability Control Module (Dsc) Communication

If you have a 5 Series, 6 Series or 7 Series BMW vehicle that enters the shop with an instrument cluster lit up with chassis and traction warning messages, and a fault check on the vehicle showing tons of faults relating to communication with the DSC, along with the DSC control unit not communicating, check fuse 2 (5 amp) behind the passenger front glove compartment panel. 

Fuse 2 on this vehicle will likely be blown. The issue is usually not related to the DSC control unit, but instead the outside painted Comfort Access (CA) door handles that are notorious for shorting out and just so happen to share a power supply with the DSC control unit (because BMW). 

The outer Comfort Access door handles have been known for physically heating up, killing batteries by waking the car up repeatedly and blowing this fuse 2. This knocks out communication to the DSC control unit. If the fuse doesn’t blow when it is replaced, clear and re run the fault check and look in the Comfort Access Control unit for specific door handle faults. 

If the fuse blows right away when replaced, the outer door handles can be unplugged fairly easily without removing door panels by releasing one screw behind a rubber plug above the door latch. 

Make sure you manually roll the latches so the handle-less door isn’t closed by accident. Once all of the handles are unplugged you can plug them in one at a time so see which one pops the fuse. If there are no faults returning, and the fuse isn’t blowing, check for a Comfort Access Handle test with diagnostic scan tool under the Comfort Access control unit. Sometimes it will reveal an ailing door handle without faults. 

Another trick: if you have access to an infrared temp gun or a thermal imager you might catch a handle heating up beyond ambient temperature. This is a good tell if you are suspecting outer door handles for causing draws as well. 

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