EWS II Explained in Detail

[ShapeShifter]

During my searches for EWS II information, I recently came across this very detailed explanation of the inner workings on a european website.

Perhaps this could be moved to the DIY for easy reference as EWS II problems become more frequent.

Workshop Hint:
On E34 an E36 models the module is located on the drivers side of the vehicle
behind the knee bolster.

On E31, E38 and E39 models the EWS II control module is located
behind the glove box in the electrical carrier

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

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 KL R. 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.
The transmitter/receiver module converts the AM signal to a digital signal and sends it to the EWS II control module.
• The EWS II control module verifies the key identification code and checks to see if the key is enabled. Upon accepting the key as valid
and enabled the EWS II control module sends a digital password to the transmitter/receiver module, which converts the data to an AM signal
and sends it to the transponder via the ring antenna.
• If the transponder accepts the password as correct the transponder releases the changing code to the transmitter/receiver module which converts this AM
signal to digital and sends it to the EWS II module.
• If the changing code received by the EWS II module is correct, the status of the BC, transmission range switch and TD is examined.
With correct input status the internal starter relay
(which incorporated into the EWS module) is energized and the starter motor begins to operate. At the same time the EWS II module sends the ISN to the DME via the single wire communication link.
• 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.


EWS II 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 ISN 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.
Note: A "Barred" key will not start the engine, it
will still unlock the vehicle.

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.
All keys either with remote or without, including
wallet and valet keys contain transponders.
8510107

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.
Transmitter/Receiver Module under Dash

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.

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 ISN 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 ISN 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.

[Boom n Zoom]

Great information PorscheDude, thanks for posting.

One {stupid} question though, I am (so far) unable to find what EWS stands for, if I find it I'll edit here.

OK well that didn't take as long to track down, I was at it all night lastnight ....

At the time of introduction the system was referred to as Electronic Drive Away
Protection which in German is Electronische Wegfahrsperre or EWS.

[ShapeShifter]

You get a gold star for today!

[ChandlerJarrel]

I just decided to find out how EWS worked and what it stood for. Did a search and this thread pops up. Strange and cool at the same time.

[yaofeng]

Save a copy on your hard disk.

http://www.unofficialbmw.com/images/BMW_EWS.pdf

[Boom n Zoom]

You get a gold star for today!

Oh cool!, I haz me ferst gowd star.


Damn yaofeng, you beat me to it

Great reading that document.

Yes , that's where my quote of EWS came from...

[AlaskaBimmer]

There actually was a batch of cars in 95 that do not have EWS II, apparently the new system was difficult to install and they got behind at the factory so a pile af at least 3 series cars made in 95 don't have it since the old system was faster to install.

I know this since I had one of those cars....I tried to order a key and the dealer ordered an EWS II key and the factory canceled the order since my car didn't have EWS II despite being a car produced after 1/1/95. The dealer then inquired about the canceled order and they got that story and I had to reorder the key in a non EWS II key. Which sucked since at the time I only had one key and it was locked in the car sitting ion my driveway for three weeks because of the screw up with EWS II....I also had to run the non EWS II JC Chip.

[Sir Montalbon]

According to some research I did on my 6/94 touring, it has EWSII. I've been talking with Wokke (of performance chip fame) and he too said that my car was EWSII despite the build date. Maybe it's a touring thing???

I'll try to find the info I found and post it in here, and I'll also pull me DME to double check when I get home...

EDIT:

Pulled my DME and it is a 404, so no, it is not a touring thing and Wokke was incorrect.

[jhughes]

My car always has a 1 second or so delay before the starter actuates upon turning the key. I'm positive it's my EWSII taking (excessive) time to read the code from the key because if I just pause in position two for a second, then crank, it cranks instantly.

[KyleCleveland]

Besides your car production date, how can you determine if your car is equipped with EWSII?

[E34nication]

Besides your car production date, how can you determine if your car is equipped with EWSII?

Pretty sure all of the EWSII e34 540/6's had a 484 code DME whereas the EWS cars had a 404 DME.

[ShapeShifter]

DME part number or Check and see if the EWS II box is in the stated location.

I believe that M60 cars with EWS II have the DME part number in ending 484.
M60 cars with DME ending in 404 have EWS I
525's have a silver label DME ending with 413 are EWS II
525's with red label 413 have EWS I

[mossyoaks]

So my 525iT was built 1/95 and has EWSII (413 silver label DME) that had to be replaced after rain water filled it's compartment.

I've found a matching DME same production month and from e34 touring.

What will I need to do to syncronize the new DME with the car? The check engine light is on but the no spark as the engine turns over.

I'm getting two codes:

26 ECU Battery voltage
220 Error EWS Interface

Do I need to swap chips?

[cornflakecwl]

OK, so my '95 525 built Oct, '94 is EWS I then. Good to know. Is there a pdf on EWS I operation as well!? I nkow it's not a convoluted or complex, but I would like to understand how its works.

[Jmac95E34]

So my 525iT was built 1/95 and has EWSII (413 silver label DME) that had to be replaced after rain water filled it's compartment.

I've found a matching DME same production month and from e34 touring.

What will I need to do to syncronize the new DME with the car? The check engine light is on but the no spark as the engine turns over.

I'm getting two codes:

26 ECU Battery voltage
220 Error EWS Interface

Do I need to swap chips?

It's explained in this PDF Yao posted, check it out.
http://www.unofficialbmw.com/images/BMW_EWS.pdf
There is some work to be done to get the EWS module and the DME to work together.

Hope this helps!

[ShapeShifter]

Or get a red label 413 DME and bypass EWS II.

[mossyoaks]

How would I bypass the EWSII?

[ShapeShifter]

I swapped in a red label on my '95 about 3 years ago and have never had a problem.

[mossyoaks]

I'll get on it first thing in the morning and report back.

[bangs]

i just swapped out my 95' 530i's engine for a 94' 530i engine, however she won't even try and engage the starter, the starter is brand new and ive quadruple checked the wiring, is it the ews system? and if so do i have to use the circumvention method prescribed above?

[Blak540i]

I also have a 1995 540 and I need to replace the dme and the one that I bought has the same problem as above. The car will turn over but not fire. I'm guessing I cant swap in a red label because I have a v8

[ShapeShifter]

You need to do the mod listed above with a 404 DME. I guess you just skimmed the post.

[Shoomakan]

Just wanted to confirm that 540i's with EWS-II came with a 484DME.

[KyleCleveland]

Just wanted to confirm that 540i's with EWS-II came with a 484DME.

Yup.

[ShapeShifter]

DME part number or Check and see if the EWS II box is in the stated location.

I believe that M60 cars with EWS II have the DME part number in ending 484.
M60 cars with DME ending in 404 have EWS I
525's have a silver label DME ending with 413 are EWS II
525's with red label 413 have EWS I