Originally Posted by CarlK920' post='374971' date='Jan 8 2007, 02:00 AM

Sorry about all the jargon! "TCU" stands for, I believe, Tele-Communications Unit. I'ts a piece of hardware about the size of a narrow 200 page book, in the trunk of the car, left side, behind a panel. It's the brains for the any phone system that is or would be in the car. The 530s made up through the month of February, 2004 had a TCU that cannot be used - by themselves -- for Bluetooth. The TCUs in cars built from that date forward can be "turned on" for Bluetooth with only a software re-programming at the dealer.
I'm reading things again here and see that you said you're just looking at buying the car. I'd ask the seller if he's using Bluetooth integrated into the car phone system. If he's not, see if you can find out what month the car was manufactured in. (see Rudy's post on that). If it's March 04 or later you can get Bluetooth turned on with some programming from the dealer, although I'm not sure how much that would cost .. Rudy or others have done that and would be better able to give you an estimate.
If it's Feb 04 or earlier build date you have two options --- replace the TCU and reprogram, at your expense, for $1500-$2000+ from what I've heard. OR, use what is called a Bluetooth Upgrade Module (BTUM). That costs about $300. For that to work, however, the car has to currently have the hardware in place for the "old" phone system that was "hardwired" into the system. Not really hardwired, since the way it worked is you had a "cradle" in the armrest and you used a phone sold by BMW -- the CPT9000, which other than the "BMW" on the front looks/works just like a Motorola V60s. So, when you wanted to use your phone/CPT9000 in the car, you put it in the cradle in the armrest and it then was integrated into the idrive/handsfree, etc. Just like the new ones with Bluetooth -- you just had to use that phone and it had to be physically snapped into the cradle.
So, the next question to ask the seller --- if he's not using Bluetooth -- is whether there is a phone in the car. Or, if you're looking at the car, open the armrest in the center console. If there has been a CPT9000 installed -- even if the phone isn't there -- you'll see somthing that pops up and has some electrical contacts at the back where the phone would go. IF that is there, then all you need is the $300 BTUM and you've got Bluetooth (of course then there are lots of issues on which phones work, etc, etc. -- but for most practical purposes, as far as I know anyway, you're basically where you'd be with Bluetooth in the TCU).
If it's a Feb 04 or earlier build date and doesn't have the cradle for the CPT9000, your only option to get Bluetooth is to "retro-fit" the cradle into the vehicle and then get the BTUM. That is what I just had done in my car -- except I haven't yet gotten the BTUM because I found a CPT9000 on ebay for about $50 and am using that for now (they were $500-600 from BMW and you can't get them anymore). For that option, the parts to put in the cradle will run you about $200. My dealer charged $150 to install the hardware. There is also some programming required -- basically to tell the car to look for the phone. In my case, they ended up having to totally reprogram the car for another issue (under warranty) so I didn't get charged for that. But, what they'd earlier told me as an estimate for that was another $100-200. That gets you the cradle that would work with either the CPT9000 OR the BTUM. Bottom line, then, is about $500 to get the cradle installed and $300 for the BTUM (although I've seen them on ebay for closer to $200 from dealers also, retail is about $300). (As an aside, and to confuse things further: on the newer cars, which have Bluetooth integrated into the TCU, they work without a cradle at all, of course. But, for some specific phones you can get a cradle installed that charges the phone and connnects it to the outside/shark fin antenna. So, if you read enough on this, you'll hear folks talking about getting a cradle for a particular brand of phone. That works only if you have the newer TCU and do Bluetooth that way -- not if you have to go the BTUM route. Then, the BTUM is in the old CPT9000 cradle and there is no way you can simply plug your phone into a cradle and have it charge and connect to the shark fin!)
Hope this answers your questions. As you can see, for the 2004 model year, there really are a number of variables!! It was the year of transition to Bluetooth and it didn't happen all at one time. So, that's why there is not a "yes" or "no" answer to your question.

Originally Posted by TexaZ3' post='375356' date='Jan 8 2007, 04:28 PM

Well, mu TCU crashed during software install on a Dec 03 Build 530i and was replaced with another TCU. But my SA told me that they still can not activate bluetooth since TCU was replaced with identical TCU and thus is not possible to activate bluetooth - how true is it? I don't know.

Originally Posted by TexaZ3' post='375356' date='Jan 8 2007, 05:28 PM

Well, mu TCU crashed during software install on a Dec 03 Build 530i and was replaced with another TCU. But my SA told me that they still can not activate bluetooth since TCU was replaced with identical TCU and thus is not possible to activate bluetooth - how true is it? I don't know.

Originally Posted by TexaZ3' post='375747' date='Jan 9 2007, 11:25 AM

How do I get to my TCU? Where is it located?