System Description

SYSTEM DESCRIPTION




The EWS II system consists of the illustrated components.


TRANSPONDER:

The word transponder is made up from transmitter and responder.

The transponder is a special transceiver in the key which communicates with the EWS control module via the transceiver module.




The transponder chip (arrowed in figure) consists essentially of the transceiver and a wireless read/write EPROM.




The transponder chip is supplied with power by the transceiver module via the ring antenna on the steering wheel lock. Thus, no battery is required in the key for supplying power. Power is supplied and data transmitted following the transformer principle. The magnetic field of the coil is switched by the transponder in accordance with the data to be transferred. The range for writing and reading data is max. 2 cm. The transponder memory contains:

- the key identification data
- a variable code

Each individual key (with or without remote control) contains a transponder chip with the above data, making it unique.




The ring antenna is attached to the lock cylinder of the ignition lock.

TRANSCEIVER MODULE




The transceiver module (S/E module) processes and controls the transmission of data to the transponder and communicates with the EWS control module. The communication occurs via a series bidirectional single wire circuit (data line).

DESIGN AND FUNCTION




The transceiver module is installed close to the steering column. it is supplied with power via terminal R. The current consumption when operating is max. 100 mA.

PLUG ASSIGNMENT:

3-PIN WHITE ELO PLUG:

Pin 1 = data line to the EWS control module
Pin 2 = terminal R
Pin 3 = terminal 31

3-PIN BLACK ELO PLUG:

Pin 1 = ring antenna connection
Pin 2 = free
Pin 3 = ring antenna connection




The EWS control module is the interface between the transceiver module, engine module and starter. Essentially it has the following tasks:

1. To call up the transponder data in the key.

2. To control the starter if the key is valid.

3. To release the DME Control Module via a coded signal if the key is valid.

4. To store the individual control module number (ISN) of the relevant engine control module.

5. To store the chassis number and the Central Encoding Key (ZCS).

6. To store the data for a total of 10 keys in all.

7. To signal which keys are blocked.

8. To monitor and protect the starter against failure to disengage.

9. To evaluate the P/N signal on vehicles with automatic transmission.

10. To evaluate the on-board computer input signal.

The control module is installed in the interior of the vehicle (see component location in the DIS). The power is supplied via terminal 30. The off-load power consumption is less than 1.2 mA.




Plug Assignment





All engine control module part numbers have been changed for use with EWS II. Engine Control Modules for vehicles equipped with EWS II and for those not so equipped are not interchangeable.

The engine control module (DME) has been redesigned so that the ignition (terminal 15) and the fuel supply are only released if a correct release signal has been passed on by the EWS control module.

The basis of this release signal is formed by the individual control module number (ISN) of the engine control module.

The Engine Control Module (DME) must identify this release signal. Only then does it release the ignition signal (terminal 15) and the fuel supply.

Consequently, after replacement of the Engine Control Module (DME), the control module number of the new engine control module must be transferred to the EWS control module by means of the procedure "EWS-DME/DDE synchronization." This synchronization procedure is contained in the MoDiC program "Programming V5.0" and later versions.

In the case of the M73 engine, the ISN of the DME Control Module is used for cylinders 1-6. The DME control module for cylinders 6-12 is 1enabled" via the CAN bus by the DME Control Module for cylinders 1-6.

The ISN cannot be altered externally.

ROUTINE FOR KEY IDENTIFICATION AND START PROCEDURE




With the ignition lock in position 1 (terminal R), the transponder is supplied with power via the ring antenna and sends the key identification code (arrows in figure) to the EWS control module.




The EWS control module demands the variable key code from the transponder.




The transponder transmits the variable key code. If the codes agree, the key is recognized as being valid and the EWS control module releases the engine control and the starter (arrowed in figure).

Note:
Approx. 350 ms are required for the complete identification process to be completed. The starter is switched off by the EWS control module if the engine speed exceeds a specific value for a predetermined amount of time. These engine speeds (determined by type of engine) and time values are programmed into the EWS control module. In the case of vehicles with automatic transmission, the setting of the gear selector is also requested and the starter only released if the gear selector is in P or N.




After starting the engine, the EWS control module generates a new variable code and sends this to the transponder (arrowed in figure).
Notes regarding the central locking system

In contrast to EWS I, EWS II functions independently of the state of the locking system. For security reasons, the central locking system is unlocked (should it be in a double locked state) when the release for starting is given.

TYPICAL ROUTINES

During manufacture or after the replacement of individual EWS components, the control modules and transponder must be initialized and synchronized. The typical routines carried out at the factory and at the dealer are described below:

PRIMARY INITIALIZATION AT THE FACTORY

The EWS control module and the 4 car keys are initialized with the key data produced at a programming station. The key data for a further 6 replacement keys which have not yet been cut are also recorded in the EWS control module. All key data (10 keys in total) are stored in the BMW database. To complete the initialization process, the individual control module number (ISN) is read out of the engine control module and entered in the EWS control module. The car is now ready to be driven.

ACQUISITION OF REPLACEMENT KEYS

It is only possible to obtain replacement keys through the Pans Department of BMW of North America. There the stored key data and password for the relevant chassis number are retrieved from the BMW database. With the aid of this data it is possible to cut a key which fits the relevant vehicle. The order to cut a key will only be accepted if all the necessary information has been provided by the customer and dealer. Each request for a key is documented, so that if necessary any queries on the part of an insurance company or other authority can be pursued. Because of the level of data protection necessary for security, and the complexity of the EWS II system, it is recommended that BMW customers be especially careful with their car keys.

A SPARE KEY SHOULD ALWAYS BE CARRIED BY THE CUSTOMER.

Beginning with key no. 5 (the first replacement key), all replacement keys are marked with an "E" on the key bit.

BLOCKING OF KEYS

It is possible to block a lost key on a vehicle with the DIS and to release it again should it be found at a later date. The procedure to be followed is described in the diagnostic program. In this instance, all keys still in the possession of the customer must be presented.

Note:
If keys are lost prior to delivery to the customer, those keys must not be blocked; rather, the EWS control module and 4 keys must be replaced. so that the customer receives a system with 4 keys and a control module containing data for a full 6 replacement keys.