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Old 10-05-2012, 01:55 PM
mej16489 mej16489 is offline
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Location: SoCal
Join Date: May 2009
Posts: 12
Mein Auto: 07 X3, 03 525i, 04 986SE
Originally Posted by rdl View Post
The ring coil/antenna does both.
See page 24 of the attached PDF.
Thanks for the pdf rdl.

I agree that doc says that the ring antenna performs both operations...

I'm beginning to think that the ring antenna is either misaligned or isn't producing a strong enough field to charge a key.

Does anyone know how to measure the inductive field? Gauss detector?!? ugh, time to dig out the box of old college textbooks... Conceivably I could use my X3 as a benchmark for the 525i

Another interesting tidbit from that doc..., "Low transmitter battery fault code storage in the GM."

Page 26 states, "As with previous systems, every press of an FZV key also provides the battery charge condition. When the FZV electronics receives a low power condition message three successive times, the GM sets a fault indicating a low battery within a specific key. The LCM is also informed via the bus system and alerts the driver via an instrument cluster matrix message."

Does this hold true for a 2003 E39? No mention of it from my wife, but maybe she didn't get 3 low power conditions in before it died completely...
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