Volkswagen 2001 Passat, Manual

Page: 45 / 64

45
The Electrics
Function
The first phase (key recognition) is identical to
that of function immobiliser II. However, the
mode of communication between the engine
control unit and the immobiliser control unit has
changed.
The engine control unit generates a number
(variable code) by means of a random-number
generator.
The engine control unit and the immobiliser
control unit each calculate a result based on a
table of formulae. The engine control unit
compares the result returned by the immobiliser
control unit with its own result. This process of
communication takes place along the CAN
databus.
If the results match up, the immobiliser control
unit allows the engine to be started.
Third-generation immobilisation
General notes:
●
The keys are marked W3.
●
For service personnel, the key adaption
procedure is unchanged. The keys are
electronically locked while being adapted. As
a result, they cannot be used to open any
other vehicle.
●
The adaptation procedure in case of
component parts replacement has changed.
CAN databus
251_037
Immobiliser control unit
Engine
control unit