EWS problem
 

Just last week one of my two keys has chosen to not talk to EWS. Turning the ignition on then to crank and nothing, not a click. Other key works fine.


Is it a key battery problem, or? I always thought EWS was like RFID communicating to the key from a ring antenna around the ignition switch.


TIA for tips.

You are right AFAIK the EWS has nothing to do with the key battery. You must have a break in the circuit board or something else going on in the key.

Yeah, cuz the dead key still works to remote lock/unlock

As 80stech stated, the EWS section in the key can fail if there is circuit board damage, such as can be caused by dropping the key onto a hard surface.

Possibly repairable but will require opening the key up.

I'm guessing by the age of your vehicle that you have a diamond key.
There is a long slender coil on the circuit board that energizes the 6-pin EWS transponder chip (also on the circuit board) when the key is switched to the crank position. The coil gets its power from the transponder/charging ring on the ignition switch. The battery on the circuit board is only required for the remote lock/trunk functions.

If the circuit or components of the transponder circuit on the board are compromised, your car will not crank. The coil is easily cut if you get too agressive with a knife blade, while trying to open the key to replace a battery. Ask me how I know. Water/moisture ingress could also be a cause of failure.

Yup. Diamond key. I've never tried opening it since the battery is still ok since 2004. I doubt there's any point trying to repair it at this point?

Repair isn't too expensive....

https://www.bmwgm5.com/Key_Repair.htm

Thanks, I'll give that a try.