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Home >> BMW >> 2005 >> 325Ci Convertible (E46) L6-2.5L (M54) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Description and Operation >> Components
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Components



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.
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