Cliff notes about remote keys:

The remote keys have 3 features/systems that are ALL independent of one another but work in conjunction with each other:

1. EWS (immobilizer)
2. FZV (remote central locking)
3. DWA (anti-theft alarm siren system)

EWS shuts down starting/ignition/fuel and uses a transponder inside the key that communicates with the EWS control module and DME/ECU. If the ISN (individual serial number) that was assigned to your car's EWS components as it came off the assembly line don't communicate with each other...the car won't start. The only way to communicate with the EWS system is with dedicated hardware/software...and the ISN can NOT be changed. The transponder's ISN (and individual key codes 1-10) are already written to your EWS control module...thus there is no "coding" that is required for a new key to start your car if you purchase a new key (any key...even the non-remote keys) from a BMW dealership. A DEAD key battery will NOT affect the key's ability to start the car....EWS is self powered thru induction (ring antenna around the ignition & induction coil inside key powers up the EWS chip inside the key which allows it to send & receive data).

FZV is the central locking system, and the remote key transmits a one-way signal to the antenna in the rear window which is then sent to a receiver located in the rear top center of the vehicle which then sends a signal to the GM to lock/unlock the doors & fuel filler flap.

DWA is the anti-theft alarm siren system, and the remote key transmits a one-way signal to the antenna in the rear window which is then sent to a receiver located in the rear top center of the vehicle which then sends a signal to the GM to arm/disarm the alarm siren.

FZV & DWA require the use of the battery inside the key to send it's signal to the car. These 2 systems also can be programmed to other BMWs that have the same set-up (and radio frequency) to lock/unlock & arm/disarm the car. This is the procedure that can be done in your drive-way to reinitialize the keys to your car (by inserting key in ignition, removing, then pressing the buttons).

The EWS transponder can't be "recoded" to another BMW...it can get out of sync...and BMW DIS/GT-1 (and some of the aftermarket software) can "resync" the EWS code tables...this can only be done with keys that have already been coded to your EWS control module (again, which have already been prepped for your vehicle when it rolled off the assembly line)...unlike the FZV/DWA features whereby any key that has the same frequency (315 MHz in the USA/Canada/Australia or 433 MHz in Europe) can be programmed to your vehicle.

Thanks Term!
I just bought a new key. Awaiting tomorrow. If someone knows hows to calibrate ews. would be great.

Thanks. How does the key loose its ews value? it still sends data.

Honestly, I'm not absolutely sure how EWS components get out of sync...other than something major or unusual probably occurs...like a power surge, or if one of the components is disconnected/swapped/replaced with another component that's not coded to the car (by owners unfamiliar with the idiosyncrasies of EWS).

One example, a forum member on a 7 series forum from Europe had purchased a blank key on eBay and had the blade cut to fit his ignition. He wanted to know why his original key no longer worked. After getting more details...he had first inserted his original key, then shut down the engine and removed the original key, then promptly inserted the eBay key which started the vehicle. He then proceeded to drive the car, but when he tried to start his car the next time (using the original key) it no longer started the car, then he tried his new eBay key, and it wouldn't start the car either. He didn't know why. Well, there's a 10 second window right after engine shut down where EWS doesn't ask for the ISN if the car is restarted...so when he inserted the eBay key, within this short window, the car started. But this caused the rolling codes to go out of sync since he used a key that wasn't coded with his car's ISN

If your car falls under EWS 3.3...it contains "rolling code technology" which changes a series of numerical tables with each use...so, if an electrical surge interrupts a component or a foreign module is inserted into the mix and a failed attempt to start the car occurs...the components can become "unsynced". But for the most part...this is a rare occurance.

thanks qsilver!
I did a lot of research on the ews and ended up purchasing a key. Inpa and Dis v57 dont have the resyn of ews/dme so i used car soft with synced them successfully but key still wont start. So i ordered a new key that should be in tomorrow. Hope it works

interesting on monday i thought about the ignition on my X, someone asked if it was easy to steal them. I have seen chinease tools to program keys in secounds. But still thought my X has a good Stock alarm and imbolizer. Should be hard to steal it. But now i Know how great it is when the key randomly looses the codes. something went wrong in the chip..

thanks qsilver!
I did a lot of research on the ews and ended up purchasing a key. Inpa and Dis v57 dont have the resyn of ews/dme so i used car soft with synced them successfully but key still wont start. So i ordered a new key that should be in tomorrow. Hope it works

interesting on monday i thought about the ignition on my X, someone asked if it was easy to steal them. I have seen chinease tools to program keys in secounds. But still thought my X has a good Stock alarm and imbolizer. Should be hard to steal it. But now i Know how great it is when the key randomly looses the codes. something went wrong in the chip..

SAME THING WITH NEW KEY!!!
lot of interior noise going on. put key in. all light when turning to start it makes on tick noise and thats it. starter doesnt turn...

Was going to post sooner that there may be a problem with the truck that is not key related. Your truck has some electrical issues.

click-click-click-click during start up - battery, isn't it?

1 click!
think its the starter.

so on m54 its under the car... any pics how to get to it... I want to try jumping the solenoid...