Yep. You're right. Any BM53 Radio from 9/2003 has the updated s/w to support Sirius and would work with your NAV. It also allows the CD Changer to be daisy changed to the Sirius receiver so you can have both.

The latest part # for BM53 is 65.12.6.976.961

This part also includes support for ID3 tag display when used with the latest (from 9/2005) BMW OEM CD Changer as well, so if they fit the very latest BM53 that will be a nice upgrade for you.

Cheers, Adrian

u know, that's the same exact part that i recently
purchased and i've yet to get my Sirius working.

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Tell us more !!!! :-)

A couple of quick checks.

Make sure you have a MKIV Nav computer
Make sure in BM Radio service mode, Radio is set to USA, otherwise Sirius won't be selectable from the MODE button.

This what the Service Measure states......

Service Measure B65-209-04 - updated on 4/30/04

Subject: E39, E46, E53 with BM53 Radio Navigation system, and DSP or Harman/Kardon Amplifier: Radio is switching from Stereo to Mono

Complaint: In FM mode only the radio sound is switching from Stereo to Mono, fading in and out.

Cause: Software error in the BM53 Radio.

Measure: On a customer complaint basis only, replace the BM53 radio. Install a BM53 radio with the new software, P/N: 65-12-4-135-562

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03' X5 4.4i Black Sapphire/Black
04' Land Rover Range Rover HSE
95' Jeep GC Ltd

i have 8 pages of info. here.

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UPDATE.....the part number they are installing tomorrow is 65-12-6-976-962

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03' X5 4.4i Black Sapphire/Black
04' Land Rover Range Rover HSE
95' Jeep GC Ltd

Interesting ... although I think you will find the part # will end with 961 !! For some reason the BMW parts database for the BM radios is off by 1 ... no idea why ?!!

Wow .. I'm just reading through now.

Your radio is good.
Your Board monitor is good.

The only thing left to try is the NAV MK IV. According to Martin at BMWNAV, he suggests that the Firmware inside the MK IV has to be 3.0 or higher for Sirius to function correctly. Perhaps thats the problem. After all, you've changed pretty much everything else !

http://www.bimmernav.com/BMW_Sirius_..._Retrofit.html

65.90-6 920 182 SW1.2
65.90-6 920 713 SW2.0 (and SW3.0 ?)
65.90-6 942 908 SW2.0 & SW2.1
65.90-6 942 910 SW ?
65.90-6 942 908-03 SW3.0
65.90-6 951 629-01 SW4.0
65-90-6-971-353-01 SW5.0

http://www.bimmerboard.com/forums/posts/168922/

Good Luck !

The odd/even number reflects new/remanufactured units.