Restraints - Air Bag Lamp ON/Fault Codes Set
SI B 72 19 06Safety Restraint Systems
October 2006
Technical Service
This Service Information bulletin supersedes S.M. B72 205 04 dated May 2004.
SUBJECT
Various Fault Memory Entries in the SBE
MODEL
E85 (Z4) from start of series production to September 2003
E63, E64 (6 Series) from start of series production to March 2005
SITUATION
The airbag warning lamp comes on and one of the following fault memory entries is stored:
FC 9913 "SBE Interruption"
FC 9914 "SBE Short Circuit"
FC 9915 "SBE Communication Fault"
CAUSE
Fault in the SBE system (Seat Occupancy Detection)
PROCEDURE
In case of a customer complaint, perform diagnostics with DIS or GT1.
Check the SBE mat as follows to narrow down the cause of the fault:
1. Move the front passenger's seat to its foremost and uppermost position.
2. Disconnect the SBE mat connector from the seat occupancy detection control unit.
3. Connect one end of the adapter cable with special tool number 61 6 043 (2-pin) to this connector and then connect the other end of the adapter cable to a multimeter.
4. Take an electrical resistance heading.
- The SBE mat has a short circuit if electrical resistance is less than 10 kOhms at the beginning of the test when the seat is occupied.
- The SBE does not have a short circuit if electrical resistance is in the mega ohm range when the seat is occupied.
5. Now switch the multimeter to diode measurement mode and take a reading in both polarity directions.
- The SBE mat has an interruption if the voltage is not between 0.6 volts and 0.9 volts in either of the polarity directions.
- The SBE mat does not have an interruption if a value of between 0.6 volts and 0.9 volts is produced when a measurement of the drop in voltage of the diode (contained in the mat) is taken in the forward direction. The forward direction is determined by test (swap polarity on the multimeter).
6. Replace the SBE if there is a short circuit or interruption.
7. If no fault with the SBE mat can be detected, the diagnostics scope should be widened to include other components in the system (control unit, etc.)
8. After the measurements have been taken and the mat has been replaced if necessary, take care to connect the connector to the control unit correctly and route the cables in such a way that they cannot tear by snagging on the feet of rear passengers.
9. If FC 9915 "SBE communication fault" is stored, do not replace the SBE mat since the mat has nothing to do with the communication fault.
- Check the connection cables between the SBE electronics and the right-hand B-pillar satellite (SBSR).
- Check the condition of the electronical contacts in the circuit between the SBE and SBSR.
- Repair as necessary.
10. Clear the fault code memory in the airbag control unit.
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