2000 X5 won't start? Please help, I need to go to work!

[TerminatorX5]

Electronic Vehicle Immobilisation System EWS 3.3

The EWS 3.3 serves as an antitheft alarm system and enables the start of BMW vehicles.
A transponder chip is integrated in each of the vehicle keys. A ring coil is fitted about the ignition lock. The transponder chip is powered by the EWS3 control unit via this coil, i.e. no battery is required in the key. The power supply and data transfer take place in the same way as a transformer between the loop antenna (coil) at the ignition lock and the transponder chip.
The key then sends data to the EWS3 control unit. If these data are correct, the EWS 3 control unit enables the starter by means of a relay located in the control unit and additionally sends a coded start enable signal via a data link to the DME/DDE. These procedures may result in a start delay of up to half a second.
Components

Data link to DME/DDE

The EWS3 control unit sends a coded enable signal to the DME/DDE via the data link. The engine cannot be started before this signal has been transferred.
Engine control unit (DME/DDE) with coded start enable input

The engine control unit (DME/DDE) only enables engine start if a correct enable signal is received from the EWS control unit.
EWS-DME/DDE interface

Identical variable codes are stored in the EWS 3.3 control unit and in the DME/DDE control unit. The value of these codes changes after every start procedure. Start enable only takes place if the code sent by the EWS control unit agrees with the code calculated in the DME/DDE control unit.
The control units are allocated only during initial programming of the DME/DDE control unit. The engine control unit then adopts the basic code of the EWS control unit.
Important
It is not possible to replace the DME/DDE or EW 3.3 control units for test purposes!
In rare cases, it is possible that the variable codes in both control units deviate from each other. In these cases, it is possible to reset both codes to the initial value via the service function DME(DDE) EWS III matching.
Key identification and start procedure


The following procedure takes place after inserting the vehicle key in the ignition lock:

• The transponder in the key is powered via the loop antenna and sends the key data to the EWS3 control unit.
• The EWS3 control unit checks the key data to ensure it is correct and only then sends an enable signal to the starter.
• The EWS3 control unit sends the variable code to DME/DDE. There, the variable code is checked against the saved variable code; if they match, the fuel injection is released.
• After the engine has started, the EWS3 control unit generates new key data (change code) and transfers them to the transponder in the key.
• A new variable code is also created and stored in the DME/DDE control unit.

Fault recognition in engine control unit


The following faults are monitored in the engine control unit:

• Interface, i.e. line to EWS control unit: In this case, the check is carried out in order to establish whether a signal is received and whether this signal is not subject to excessive interference.
• Variable code: A check is conducted as to whether the variable code which is sent by the EWS control unit agrees with the value calculated in the DME(DDE) control unit.

Engine start is inhibited if a fault is detected.