Specifications

Testing Testing Immobilizer (EWS) Systems

11. The EWS II sends the ISN code to the DME. If the ISN code matches the code stored in the

DME, the drive away protection is cancelled and the engine is allowed to start.

NOTE:

i The data communication required for engine starting as described above takes place in

milliseconds—there is no noticeable delay during starting.

IMPORTANT:

Starting problems caused by faulty ignition keys are common. Always have the owner bring in all

keys for use in diagnosing a no-start condition.

Once the identification and verification of the data codes are complete, the EWS II sends a new

changing code to the key for the next starting procedure. The changing code is a random number

that is generated by the EWS II control module. The transponder stores this code until the next

time the ignition is switched on.

The EWS II system is totally independent, in operation, from the mechanical key other than the

key fob which contains one of the components. The system features a wireless communication

link between a programmed EEPROM (transponder chip) housed in the ignition key and the

EWS II control module. The system will not allow the starter to engage until a properly-coded

transponder key is inserted into the ignition lock cylinder. The transponder chip operates

independently from the mechanical key blade and tumblers.

NOTE:

i EWS II may have auto start recognition which disengages the starter motor as soon as the engine

is running.

Replacement of DME and EWS II Control Modules

Currently, replacement EWS control modules are ordered from the factory and come programmed

to recognize the VIN specific key codes. After installing the EWS II control module to the vehicle

harness, it will need to be ZCS coded. If the original DME (ECM) was previously replaced, the

EWS II control module must be synchronized with the DME by transferring the new DME ISN to

the EWS II module. If the vehicle has the original DME and the EWS module is replaced, then

synchronization or alignment should not be necessary.

NOTE:

i There is no limit to the number of times the ISN can be changed in the EWS II control module.

EWS II DME/EWS Synchronization or Alignment

If a factory-coded, replacement EWS II control module is ordered and the vehicle will not start, if

possible, check the service records if the original DME control module has been replaced.

If the DME has been or is replaced, the ISN of the replacement DME control module must be

aligned with the EWS II control module. The alignment procedure copies the ISN from the new

DME control module and installs it into the EWS II control module. If this task is not carried out

properly, the engine will crank but not start.