Thread: Key Fob probelm
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Old 06-09-2012, 05:04 PM
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QSilver7 QSilver7 is offline
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Location: Northeast Indiana
 
Join Date: Aug 2008
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Mein Auto: 1997 740iL / 2006 X5 4.4
EWS transmits on 125 Khz AM signal - FZV/DWA transmits on 315 MHz RF signal

It's simple to understand once you know how the 3 features in the remote key (EWS/DWA/FZV) all work in conjuction in the key...but are 3 independent systems. Take note that the information below mentions DIS & MoDic in communicating with the EWS system...this is now done with BMW's GT-1 (MoDic is now outdated). That is how you communicate with EWS other than...the data between the EWS components communicate with each other over the 125 KHz AM radio frequency.

The EWS system communicates on a totally different RF (radio frequency) than the DWA & FZV features of the key. There could be multiple reasons why the car's didn't start in the scenarios you presented. It could be as simple as the key was turned too fast in the ignition not allowing the Ring Antenna to read the key's ISN code...which is required to allow the car to start.

EWS is different from FZV & DWA in one major way in that it operates using an ISN (individual serial number) that is used in all of the EWS components. The EWS chip (inside the key) is a transponder...and a transponder communicates in 2 directions...it receives as well as sends communication over a 125 Khz AM signal that is sent from the EWS control modoule to the Ring Antenna (or the transmitter/receiver if your car has EWS II). The chip inside your key comes from BMW already with the transponder coded with the ISN that is specific to your car's VIN. (btw, did you remember if you even tried to start your E46 with the new key before programing it to lock/unlock & arm/disarm the car?) There usually is no need to have to do anything when purchasing a new key for it to be able to START your car...unless the EWS components have become unsynced. But you DO need to program the FZV/DWA so that you can lock/unlock & arm/disarm the car.

And even if you do reinitialize/program a new remote key in the dealers parking lot...when you get home...your old remote key will still start the car but won't lock/unlock & arm/disarm the car because it will not have the same coding due to it being absent from the process back in the dealer's parking lot. To get both keys to perform FZV/DWA...you will have to reprogram both keys again, during the same session.

The DWA/FZV features are transmitted over a 315 MHz radio frequency (one-way communication only) to the receiver that is in the C-pillar (in North America...Europe and other markets use 433 MHz). That data is then passed on to the GM (general module) & DME.

Again, a new remote key purchased from the dealership...comes already programmed with your car's ISN which is based specifically on your car's VIN (which must be presented along with proof of ownership before the key is ordered):

(TiP: pay attention to the WORKSHOP HINTS that is in the gray boxes in the info below & in the info I previously posted)






Also, depending on your e39's build date...it could have EWS II, EWS 3.2, or EWS 3.3...obviously each iteration brought some changes (like combining the features of the transmitter/receiver into the EWS control module starting with EWS 3.2:

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Last edited by QSilver7; 06-09-2012 at 05:09 PM.
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