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Old 01-14-2013, 10:04 AM
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QSilver7 QSilver7 is online now
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Location: Northeast Indiana
Join Date: Aug 2008
Posts: 9,160
Mein Auto: 1997 740iL / 2006 X5 4.4
These remote keys confound so many's some info that may help understand the key...although it may do nothing to help your problem.

The remote keys contains 3 features/systems that are all independent of each other but work in conjunction within the housing of the key and the 3 operating systems:
  1. EWS - immboliizing "drive-a-way-protection" that uses a transponder (transmits & receives data) that shuts down fuel/spark/ignition until an ISN (individual serial number) that is shared by all the components of EWS verify that all the ISNs are the same. This feature is self-powering and communicates on a 125 KHz AM signal that is sent from the EWS control module to the Ring Antenna (around the ignition) which then sends the signal to the EWS EEPROM (transponder chip) which is soldered to the IC board inside the key (on the e53's remote key). The only way to communicate with the EWS system is through dedicated hardware/software (there's no driveway initializing short-cuts that communicate with EWS)
  2. DWA - anti-theft alarm siren system ... transmits a 315 MHz or 433 MHz signal (one-way) to the receiver in the roof of the e53 which then sends a signal to the GM to arm/disarm the alarm siren and monitoring sensors (interior/tilt/hood/doors/fuel filler door) as well as activate the DWA LED (clown nose) beneath the rear view mirror. This feature is powered by the rechargeable battery that is inside the key. This feature can be initialized to other BMWs that use the same radio frequency and system (e46/e38/e39/Z3/e53/Z4).
  3. FZV - keyless locking/unlocking of the central locking system ... also transmits a 315 MHz or 433 MHz signal (one-way) to the receiver in the roof of the e53 which then sends a signal to the GM and on to the central locking system to lock/unlock the doors/tailgate/fuel filler door. This feature is also powered by the rechargeable batterythat is inside the key. This feature can also be initialized to other BMWs that use the same radio frequency and system (e46/e38/e39/Z3/E53/Z4).

When you opened your spare and replaced the long did you allow the key's battery to recharge? The ability to UNLOCK the vehicle but not lock one of the fail-safes of the keyless entry system that is an indicator of low battery voltage (in the key). It can take up to 30 hours to recharge a fully discharged key (see the 3rd bullet in the remote key info below:

To get your original key working again, you may need to take it to a dealer...or find someone that has the hardware/software that can communicate with the control modules. It sounds like you need to resync your key with the other EWS modules if it no longer starts the car. Again, the key does NOT require the battery inside the key to start the car...but it does need to be synced with the other EWS components to work properly (see the very last sentence in the info below).

Also note that the FZV signal is picked up by the antenna built into the rear window, which then passes that signal on to the receiver in the roof...where as the EWS signal is picked up by the ring antenna around the ignition...again, these are 2 separate systems that are working in conjunction with each other:

FYI: below is the instructions for reinitilizing the FZV/DWA (lock/unlock & arm/disarm) features of the remote keys. The instructions must be followed to the "T". Do NOT fudge, skip, combine, ignore any of the steps...and ALL remote keys must be programmed DURING the SAME session. Any remote key not initialized during the same session will no longer have the ability to lock/unlock & arm/disarm the car. It will start the vehicle but the FZV/DWA feature will no longer work:

Q {BMW CCA Member #191509}
2006 E53 X5 4.4i (Sterling Gray) 12/05 mfg date <<~>> 97 740iL (Arctic Silver) 3/97 mfg date
99 540iT (Orient Blue) <<~>> 95 525IT (Alpine White)
91 735iL (Schwarz Black) <<~>> 85 325e (Bronzit)

Last edited by QSilver7; 01-14-2013 at 10:08 AM.
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