Specifications

18
Testing Testing DAS (Immobilizer) Systems
DAS 2b
DAS 2b (170/129/140) was introduced in 1998. This system uses a three-button remote with
both infrared and radio wave transmissions. The vehicle is locked or unlocked when either the
infrared or radio transmits an uninterrupted signal. The three remote key buttons are for:
• Locking doors
• Unlocking doors
• Unlocking the trunk
Note the following regarding DAS 2b systems:
•
DAS 2b also added convenience closing and summer opening of windows and sunroof
(uses infrared signal only).
• DAS 2b also permits global locking/unlocking (doors, trunk lid, and fuel filler flap) or selective
unlocking (driver's door and fuel door only).
• When the vehicle is locked using the remote control, the hazard lights flash 3 times and
when unlocked, they flash once.
• For both DAS 2a and DAS 2b, new replacement keys do not require any special learning
procedure to start the engine—the emergency mechanical key also contains the transponder
to operate the ignition switch.
• For 1998 ML 163 series, key synchronization activation requires a scan tool procedure which
the Scanner currently does not perform.
z To synchronize the remote:
1. Turn the ignition ON.
2. Turn the ignition OFF.
3. Remove the key from the ignition.
4. Press the remote button.
The remote should now lock and unlock the vehicle.
DAS 3
DAS 3 is the most sophisticated and advanced generation of DAS. DAS 3 was introduced on the
C, E and CLK class in 1997 and the S class in 1998 (210/208/202), increasing each year with
more models phased in.
This system has all the same features of DAS 2b except that the ignition switch is now fully
electronic (the mechanical key is used only for vehicle access). This means that with DAS 3,
both access and drive authorization are fully electronic.
Access authorization using the remote key uses both infrared and radio transmission, but the
electronic key drive authorization only uses infrared. The electronic key transfers a radio wave
code to the electronic ignition and starter switch (EIS).
Table 4-5 DAS 2b characteristics
Triggered By Signal Type
Authorization
Checked By
Operator
Feedback
Authorized
Start Result
Transponder in
key
Inductively
coupled RF
RFL N54/3 None
NO fuel injection;
may crank briefly