EWS II
EWS II
Starting with 1/95 production, all vehicles were equipped with a new EWS system, EWS II. This change was once again brought about to meet the next level of compliancy with the European Insurance Commission regulations.
Purpose of The System
Changes to the European Insurance Commission regulations made it necessary to introduce a new theft protection system with greater capabilities and a higher level of security. The EWS II system operates independent of the mechanical key. The mechanical key only makes a request of the vehicle starting system. Verification of the key electronically is required before the starting procedure is initiated.
The system features wireless communication between a programmed EEPROM housed in the ignition key and the EWS II control module. A key which is properly coded to the EWS II control module is required before starting operation continues. The EWS II and the DME control modules are synchronized through an Individual Serial Number (ISN).
The ISN, stored in the EWS II, must match that of the DME every time the ignition is switched "ON" before engine operation is allowed.
EWS II was installed on E31, E34, E36, E38 and E39 vehicles.
Major components of the EWS II system are:
- Key with Transponder
- Ring Antenna
- Transmitter/Receiver Module
- EWS II Control Module DME Control Module
System Components
Key with Transponder
Four keys are initially supplied with each vehicle. Each key contains a wireless electronic chip (transponder chip). The function of the transponder is to receive and transmit data to the EWS II control module. The transponder contains a wireless read/write EEPROM in addition to a small capacitor and coil for self power capabilities.
The functions of the EEPROM are:
- Store codes for key identification, password and changing codes.
- Receive and respond to coded messages from the EWS II control module.
Power for the transponder is produced through the inductive coil and stored in the capacitor. Each time the key is inserted into the ignition AC voltage in the antenna ring induces voltage in the inductive coil.
KEY NOTE:
Keys have temperature operating range of -40 ° to 80 °C.
Keys are shock resistant from a height of 10 meters.
Ring Antenna
The Ring Antenna is an inductive coil installed around the lock cylinder which provides power for the transponder in the key and the communication link (antenna) between the key and the transmit/receive module.
Transmitter/Receiver Module
The Transmitter/Receiver module supplies power to the transponder through the ring antenna and controls the flow of data between the transponder and the EWS II control module.
Data transmission between the transmitter/receiver module and the transponder takes place over a radio frequency of 125 KHz amplitude modulated AM signal.
The transmitter/receiver module converts the analog data received through the AM signal to digital data and transfers it to the EWS II control module over a single wire bi-directional data interface.
Workshop Hint:
On E34 and E36 models the transmitter/receiver module is located under the dash near the steering column.
On E31, E38 and E39 models the transmitter/receiver module is located in the steering column cover on the right hand side of the column.
EWS II Control Module
The EWS II Control Module is linked to the BC, GM, DME, Trans Range switch and the starter for drive away protection operation. The module incorporates an integral starter relay and stores data and codes for communication with the transponder chip.
The function of the EWS II module is to provide improved drive away protection for the vehicle and it incorporates many features of previous systems:
- Lock out of the starter when the code function of the BC is set.
- Disable injection and ignition through the DME.
- Prevent starter engagement with engine running.
- Recognition of Park/Neutral position with automatic transmission.
New features that have been added:
- Disable injection, ignition and starter operation until a correct key is recognized.
- EWS and DME synchronization through the use of the ISN.
- Release of double lock when a correctly coded key is switched on.
The EWS II control module stores the following data for the key transponder inter-link:
- Key identification code- up to 10 keys.
- Key password.
- Changing code- up to 10 keys.
Workshop Hint
On E31, E36, E38 and E39 models the EWS II control module is located behind the glove box in the electrical carrier.
On E34 models the module is located on the drivers side of the vehicle behind the knee bolster.
Typical component locations E36 shown
DME
The DME is redesigned to incorporate the new ISN code. As of production 1/95 all DME control modules will contain the unique ISN number and will not interchange with previous DME's. The following new features are added to the DME:
- Unique ISN assigned to DME during manufacture, it can not be changed, altered or overwritten.
- The BC code input to the DME is eliminated.
- The DME and EWS II control module must be synchronized. The DME sends the ISN to the EWS II module which stores the number for replay to the DME
- The ISN received from the EWS II module during start-up is compared to the internal SN of the DME. The numbers must match before the start operation is allowed to continue.
- The ISN is sent to the DME continuously by the EWS II module with the key on.
- The DME will ignore loss of the ISN after the engine is running.
- The DME retains the SN information from the EWS II module for 10 seconds after the ignition is switched off.
Restarting or switching the ignition on within the 10 seconds cancels the key identification process.
Workshop Hints:
The DME is located in the E-Box.
Remember the EWS-DME link stays active for 10 seconds while testing keys for proper operation.
Principle of Operation
The starting sequence involves communication between all the components of the system. Any break-down in the communication process will result in a no start condition. The sequence of events for vehicle starting is as follows:
- The key is inserted into the lock cylinder and switched "ON". The transmitter/receiver module is powered through KLR. The transmitter/receiver module sends a 125kHz. AM signal to the ring antenna. The AM signal induces voltage in the key coil and powers up the transponder.
- Powered up, the key transponder sends the key identification code to the transmitter/ receiver module via the 125kHz AM signal (1). The transmitter/receiver module converts the AM signal to a digital signal and sends it to the EWS II control module (2).
- The EWS II control module verifies the key identification code and checks to see if the key is enabled (3).
- Upon accepting the key as valid and enabled the EWS II control module sends a digital password (4) to the transmitter/receiver module, which converts the data to an AM signal (5) and sends it to the transponder via the ring antenna (6).
- If the transponder accepts the password as correct the transponder releases the changing code (7) to the transmitter/receiver module which converts this AM signal to digital (8) and sends it to the EWS II module (9).
- If the changing code received by the EWS II module is correct, the status of the BC, transmission range switch and ID is examined. With correct input status the internal starter relay is energized and the starter motor begins to operate (10). At the same time the EWS II module sends the ISN to the DME via the single wire communication link (11).
- If the ISN code stored in the EWS II module matches that of the DME, the drive away protection is cancelled and injection and ignition is enabled.
- During the process of sending the ISN to the DME, the EWS II module sends a new changing code to the transponder through the transmitter/receiver and ring antenna.
The transponder stores the changing code until the next starting sequence.
Workshop Hints:
The entire process takes place in under 750ms.
If the starter operates, the key has been recognized as OK and the key requires no further diagnosis. Check status of ISN in DiSplus or MoDic.
Recognition of a valid key by the EWS II module causes it to send an unlock signal to the GM if the vehicle is in double lock.
Replacement Procedures
Keys
Up to 6 additional keys may be ordered as replacement keys. The EWS II control module is codeable for only 10 keys (4 delivered with vehicle and 6 replacement).
EWS II Control Module
Replacement EWS II Control Modules must be ordered VIN specific. EWS II modules contain the VIN and coding from the factory to recognize the key codes. Modules from other vehicles will not recognize keys as being valid and not start the engine.
EWS II Control Modules store the Central Coding Key (ZCS) and the VIN. If the EWS II control module is replaced the system must be ZCS coded (SIB 61 02 96 and TRI 61 01 95).
The EWS II module must be synchronized with the DME (aligned). There is no limit to the number of times the ISN may be changed in the EWS II module.
DME Control Module
The DME Control Module is not ordered VIN specific and must be programmed during replacement. The SN from the new DME must be transferred to the EWS II module using the DISplus or MoDic.
Key Activation
Keys that are lost or stolen may be deactivated or made to not operate the starter functions. The SERVICE FUNCTIONS of the DISplus or MoDic for EWS II contains a "Bar/Release Code" function that activates and deactivates keys of the EWS II. Any key may be "Barred" except the key in the ignition at the time of deactivation. The lost or stolen key can be identified by the identification of the remaining keys.
There is no limit to the number of times a key can be activated/deactivated.
EWS II Update
Beginning MY 1997 E31 and E36 vehicles with manual transmissions were updated to include a clutch pedal position switch. The clutch switch signal is provided by a hall-effect sensor providing a high signal when the clutch is depressed.