Specifications

17
Testing Testing DAS (Immobilizer) Systems
NOTE:
i On some models, the green and red LEDs on the rear view mirror flash alternately if the engine
will not start because DAS is activated.
DAS 2a
DAS 2a was used from January to June in 1996 on the E420. Activation and deactivation no
longer occur automatically when locking or unlocking the car. Previously, if the vehicle was
unlocked, DAS allowed the vehicle to start. The change with this system is that the locked or
unlocked condition of the vehicle no longer affects the ability of the engine to start. In other
words, the RCL and DAS functions are now separated.
DAS 2a introduced the transponder, which adds another level of security to the ignition switch.
For the key to work in the ignition, radio wave transmission from an in-dash transmitter is sent to
the transponder in the key, which is then sent from the key to DAS for evaluation. If DAS accepts
the code, then the ignition switch operates to start the vehicle.
The transponder system automatically changes the codes each time the key is placed in the
ignition. Each key has a uniquely-coded chip assigned to the mated DAS control module. The
vehicle originally came with 2 remote keys and one valet key.
NOTE:
i DAS 2a can be identified by the presence of a transponder ring around the ignition lock and the
absence of exterior IR receivers.
DAS X
DAS X was installed on all 1997 vehicles starting in June 1996. This system uses two separate
control units, one for DAS and one for the Remote Central Locking (RCL). It uses a key
transponder like the DAS 2a system and has similar functionality. This system also added
exterior RCL IR receivers.
Table 4-3 DAS 2a characteristics
Triggered By Signal Type
Authorization
Checked By
Operator
Feedback
Authorized
Start Result
Transponder in
key
Inductively
coupled RF
RCL N-54 Mirror LEDs
NO fuel
injection
Table 4-4 DAS X characteristics
Triggered By Signal Type
Authorization
Checked By
Operator
Feedback
Authorized
Start Result
Transponder in
key
Inductively
coupled RF
DAS N54/1
Mirror LEDs on
202/210
NO fuel injection;
202 no crank