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Old 10-11-2011, 08:35 AM
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QSilver7 QSilver7 is online now
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Location: Northeast Indiana
Join Date: Aug 2008
Posts: 9,583
Mein Auto: 1997 740iL / 2006 X5 4.4
Originally Posted by cn90 View Post
But I thought you need two (2) requirements to start the E39:

1- the mechanical portion: ignition tumbler to start the car
2- the EWS system, with they key out, the chip in the key is out of the car, how can the car run? Maybe it is within some distance (in the owner's pocket) so the ECU can recognize it? What happens if the owner (key in pocket) walks far away from the car, does it still run?
EWS prevents "STARTING" if the transponder isn't read...the issue here is that the car is already running...and the OP can't turn it off. Once the car is running...the DME "ignores" the loss of the ISN (individual serial number).

There's also a brief 10 second window where you can start the car with a key that has lost its EWS transponder because the DME/ECU will retain the ISN sent to it by the EWS-CM.

I assume this small window is used for quick restarts. For instance, if you pull into your drive/garage and turn the car off...then immediately remember that you forgot to pick up Ashton or Jamie from kindergarten...or you forgot to pick up that loaf of bread & gallon of you restart the car to head back out...the EWS communication between the ECU/EWS-CM/Ring Antenna/Key is cancelled and the car can be restarted without all of the EWS communication scenario taking place.

See text in red box which explains the 10 second cancellation of the "key recognition" sequence of EWS...and in the 2nd pic below...see the "WORKSHOP HINT" which warns to wait 10 seconds between checking keys because of how the ISN info is either retained or ignored during that 10 second period:

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; 10-11-2011 at 08:41 AM.
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