Some information on the BMW FZV Antenna Amplifier
I just finished doing a little testing on the FZV antenna amplifier. No, mine isn't bad. I'm doing this because there have been a few people telling me that they can't code their key to their car (See recoding procedure) and are wondering if replacing the relays will help. NO, it won't help. The relays will only help in cases where one or more door locks don't lock or unlock. If your key doesn't start the car please check out my EWS web page. If your car doesn't do anything when the key fob buttons are pressed, no locking, no unlocking, no trunk release, no interior lights (when unlock is pressed), no alarm beep then recoding may help. If any one of those do function then recoding will NOT help. The key and car are already in sync. If the car intermittantly responds to the key fob or if there is not response and key recoding didn't help then there are several possible causes. It could be the key fob itself or the battery, it could be the antenna on the rear windshield (in the rear view mirror on the convertible) it could be the FZV antenna amplifier, it could be the GM5 or the wiring. So far I've only seen problems where the FZV antenna amp was bad and replacing it solved the problem. I've heard on the forums that replacing the battery has solved problems for people.
Ok, so let me start off with a brief explanation of how the whole system works. When a button on the key fob is pressed a digital message is modulated on a 315MHz (453MHz on some cars) carrier and transmitted like a little radio station. An antenna on the rear window glass (in the rear view mirror on convertibles) receives the RF signal and sends it to the FZV antenna amplifier located on the C-pillar usually on the left hand side (on convertibles it's located in the rear view mirror). Here it is on my 4-door with the C-pillar cover removed.
The FZV antenna amplifier demodulates the signal and sends a +5V digital baseband signal to the GM5 (aka ZKE5) module. The output on the FZV module is pin 3 and input on the GM5 module is X253 pin 49 (X253 is the center connector on the GM5). If you are looking at the BMW WDS, the FZV antenna amplifier is module "N8" and the GM5 is module "A1". Below are a couple scope captures looking at the baseband signal out of the FZV module. The picture on the left is the whole message. It varies in length from press to press from about 0.19 seconds to about 0.32 seconds. This line normally sits at +5.0V and drops to nearly zero to indicate presence of a RF signal from the key fob. If you don't have an oscilloscope you can check for the presence of a signal using a simple DMM. If you use the DC Volts scale and measure from this signal to ground you will measure +5.0 Volts and when a button is pressed the line should drop to a minimum of +2.5 Volts for a fraction of a second. Don't worry if you don''t see +2.5 Volts, but, instead see some other number that is between +2.5 and +4.5, this is fine. It all depends when the meter sampled the signal. You can also set the meter to AC Volts. In this setting you will see zero volts most of the time and it will jump to about +2.5 Volts when a signal from the key is received. If you see that you are getting a signal on this line and following the key recoding procedure doesn't work then it's probably the GM5 module, but, I think this would be a very very rare failure mode. More likely you will not see a signal and the problem is in the wiring, the FZV antenna amplifier module or in the key fob. If you have had a problem with your key fob not working with the car and found out what was causing the problem please shoot me an email (scott@bmwgm5.com). I'd love to know what resolved the problem in your case.
E46Fanatics thread on the differences between the 1999-2001 and 2002-2005 FZV antenna amplifiers. http://forum.e46fanatics.com/showthread.php?t=662688
New Information:
Jez just emailed me to say that his problems are fixed. In his case the car
stopped responding to the keys. Multiple attempts to reprogram the car to the
key didn't work. He measured the signal going into the GM5 from the FZV and
there was no signal, just 5V with no dip when the key fob buttons are pressed.
He finally located a FZV for his E46, 3-series wagon at a salvage yard and installed
it. Presto everything works fine now. Key reprogramming worked the first time,
alarm arms & disarms, remote trunk release works, remote door locks work.
Problem was not the GM5 module or the key fob battery like he initially guessed.
Thanks Jez for your story.
Connector X1143 pin 3 sends the demodulated baseband signal from the key fob
to the GM5 module.
Connector X424 supplies the FZV antenna amp with +12V from Fuse #7
Connector X01021 Connects to the radio head unit for AM/FM reception
Connector X01022 Connects to the radio head unit for AM/FM reception (Diversity)
Connector X01023 Connects to the conductive lines on the rear window glass (the
actual antenna)
Picture <-- Picture of the FZV module
out of the car
Picture <-- Picture of the FZV
module, component side
Picture <-- Picture of the FZV
module, solder side
Picture <-- Close up picture of FZV
key fob section
Picture <-- FZV on a convertible
FZV Antenna Amplifier repair service. I am now doing repairs on this module. Cost is $65 including return shipping within the US. This module takes a while to work so I don't offer my drive up repair service. Just drop off & pick up next day or mail it in. To arrange a repair either contact me via email at scott@ bmwgm5.com or give me a call at 310-283-4273. I will not give you my address over the phone due to too many modules being sent to the wrong address because they wrote it down wrong. My address is only give via email. Before I allow you to send a module to me I need to hear your symptoms and determine if the problem sounds like a FZV antenna amp problem.
GM5 Repair Service web page.
To V23078-C1002-A303 web page.
To V23072-C1061-A303 web page.
BMW General Module II (GM2) Page
BMW General Module III (GM3) Page
