Ring aerial

The ring aerial is used for communication between transponder chip (in the ID transmitter) and the Car Access System (CAS) or front electronic module (FEM) or Body Domain Controller (BDC).

In unfavourable situations, it is sometimes not possible to find the ID transmitter in the passenger compartment. In this case, the Car Access System (CAS) or front electronic module (FEM) or Body Domain Controller (BDC) will initiate a Check Control message in the instrument cluster.

When a corresponding message is received, the ID transmitter needs to be held against the marking on the steering column. After successful identification, this enables the Car Access System (CAS) or the front electronic module (FEM) or Body Domain Controller (BDC) to issue the start enable.

Within 10 seconds of placing the ID transmitter against the marking, press the START-STOP button. The engine starts, providing that the brake pedal (automatic transmission) or clutch pedal (manual gearbox) is depressed at the same time. Driving readiness is established for hybrid cars and BMW i vehicles.

Functional description

The communication between transponder chip and Car Access System (CAS) or front electronic module (FEM) or Body Domain Controller (BDC) is inductive. Electromagnetic fields are transmitted via the ring aerials.

If the transponder chip is located in the reception range of the ring aerial, signals are transmitted via an electromagnetic field. The transponder chip is activated by induction, so that it then communicates with the Car Access System (CAS) or front electronic module (FEM) or Body Domain Controller (BDC).

The following graphic shows the ring aerial using the example of F01.

Item Explanation Item Explanation
1 Ring aerial 2 two‐pin plug connection

Structure and inner electrical connection

The ring aerial is connected to the Car Access System (CAS) or the front electronic module (FEM) or the Body Domain Controller (BDC) via a 2-pin plug connection.

Item Explanation
1 Ring aerial

Pin assignments

Pin Explanation
SIG Coil connection
SIG2 Coil connection 2

Signal shape and setpoint values

Observe the following setpoint values for the ring aerial:
Variable Value
Supply voltage 6 to 16 V
Frequency range 125 kHz
Inductance of the coil 1.33 mH
Temperature range -40 to 80 deg C

Diagnosis instructions

Failure of the component

If the ring aerial fails, the following behaviour is to be expected:

  • Fault code entry in Car Access System (CAS) or front electronic module (FEM) or Body Domain Controller (BDC)
  • Check Control message in the instrument panel

 

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