Re: EWS II in a nutshell

[XYOBGYN@xxxxxxx]

Hello list.

Finally, something I can discuss intelligently.

My local Mentor Al Valenzo at Patrick BMW, the Bentley manual, and some 
factory handouts gave me the information needed to tackle a Euro 3.2 dual 
vanos transplant into my EWS II 95 M3 LTW successfully.

Here's a nutshell of how EWS II works.

Components:
Coded Key: Each key has a chip in it with a unique code embedded in it.  The 
keys are not powered, but they are read by an.....

Ignition switch with an antenae ring.  This ring charges up the key's 
capacitor to hold enough voltage to activate a coded chip on it that 
broadcasts an analogue signal that is picked up by the antenae ring.  This 
signal is sent to a....

FM transmitter, which converts the signal to a digital one.  This signal is 
then passed to an....

EWS Box, which is unique to the vehicle. (the ignition switch and FM 
transmitter are not).  The EWS box has encoded in it 10 keys from the 
factory.  These can NOT be altered at anytime.  They do have an attached code 
for each key that is either activated or inactivated.   Four keys are given 
to the new car owner, and the factory has set them as "ON" at the time of 
purchase.  (Valet, small wallet sized one, and two regular ones if I recall). 
 The point here is that if you lose a key, the dealer can turn it "off" in 
the EWS module, and it can not be used to steal the car.  Also, and this is 
important, if a new key is ordered, it can only be one of the remaining ones 
stored at the factory.  Upon arrival at the dealer, the EWS must be coded, 
and have that key turned "ON", or it won't work.  This prevents a stolen key 
from the factory from working on your car, or a dealer's employee from easily 
ordering a key and just stealing your car without the mechanic first turning 
on the key.  Needless to say, if you "use up" the 10 keys, a NEW EWS box with 
10 new keys codes must be ordered.  The EWS box also has a programmable area 
for a ECU ID number.  This CAN be changed, and at the factory is programmed 
in with a unique code from the engine's .....

ECU.  The ID number for this component of the EWS system is unique to that 
ECU.  It is NOT alterable inside the ECU, and is the only part of the engine 
per-say that makes it THAT specific engine as far as the EWS system is 
concerned.  If an ECU burns out, or is damaged, a new ECU can be ordered, 
but, the EWS box will have to be programmed to take on the new ECU's ID 
number.

How it all works:

When you put a key into the ignition switch, turning the switch powers the 
antenae ring to charge the key.  This in turn causes the key to broadcast a 
ID number, which is read by the antenae.  The signal is then digitized if you 
will, and sent to the EWS box.  The EWS box then checks the key against the 
ones stored in it, and if its valid the process continues.  (there is 
actually an additional layer of complexity with rotating and randomly 
generated numbers that goes on between the keys and the EWS, but its not 
relevant at this point)  Next, if the key is valid, the EWS asks the ECU for 
its ID number.  If the ID number is the same one that has been stored in the 
EWS box, THEN the EWS unit tells the ECU that its OK to start the engine.

Basically this system prevents you from stealing a car unless you have a 
matched key/EWS/ECU that you can swap into the car your're trying to steal.  
Then it would work.

To the best of my knowledge, you can not activate or inactivate keys without 
MODIC.  Nor can you alter the stored ECU's ID in the EWS without Modic.  This 
process is referred to as alligning the EWS by the techs.

In my car, I didn't want to rekey the cyclinder or the doors, or the trunk, 
so I simply taped a correct key from the original donor engine into a spare 
antenae, and stuffed it under the dash.  I used the donor EWS box and of 
course ECU, and just used my factory key in the column to turn on the 
ignition line... that caused the other key to be read, and all numbers 
matched, and the engine works fine.

Well, thanks for the bandwidth, and admittedly, this was a large nutshell.

Alex Lipowich
91 Z1 
95 M3 Euro 3.2 LTW,  #8 ASR 
97 Z3 2.8

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