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Hi all,

My 2004.5 GLX came "pre-loaded" with OnStar. I don't plan on using it (beyond the free year) but I do want to see if I can use the handsfree functions. OnStar has a "personal calling" feature that is both cumbersome and expensive that I don't want to use. I believe it uses ATT wireless and I have (and would like to keep) Cingular.

What it does do is mute the car's stereo and direct the phone call through the front speakers. It also uses the microphone located in the moonroof control console.

What I like about this setup is that there are no visible signs of a car kit. The OEM Look.

Ideally, I would like to use a Nokia Bluetooth Car Kit behind the scenes and either use the existing microphone, or fit the kit's microphone in the space for the microphone, and use the car's speakers.

Does anyone know (or know how to find out) if the mic is an onstar specific mic or is it a mic that is compatible with Nokia Car Kits? (I only ask because Nokia makes the kits offered on non-us VW models.)

Has anyone tried this or have experience with this type of wiring that might be able to tell me if there are any obvious road blocks here?

Thanks!
Dave
 

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Westerdave,

There is an OEM mic that will connect to the nokia car kits. Click on the link => http://www.clubb5.com/forums/viewtopic.php?t=62974&highlight= . The post is mainly about those of us with the Navigation system, but mid-way on page 2 there's a post by Tongsli with the link to the OEM microphone at impex. The part in his post is for a jetta/golf, but I think it may work in the passat since they appear to use the same overhead consoles. It's about $50. The microphone for a passat is around $83, however I don't have the part number for the passat. You could PM Tongsli and see if he could help out.

Impex is located in Cockeysville on York Rd, so if you decide to purchase it you can pick it up from them and save shipping. They are not a true retail location, but they will allow you to pick up orders. I ordered a charcoal cabin filter from them and picked it up. Nice guys.

HTH

Mike
 

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Discussion Starter #3
Thanks for the feedback. I called the guys at Impex and they can order the part and it does fit the Passat, but they couldn't tell me anything about it.

I went out to the car opened the overhead compartment (by the moonroof knob) and the OnStar mic wire is right there. I'm wondering if I can't just tap in to that wire and connect it to the car kit with the right connectors. I don't plan on using the OnStar beyond year 1.

Sounds to me like this is going to be a trial and error project if I want to try to use the existing mic ... :thumbdow:
 

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Cellular Standardization Insights

Westerdave ~

Although I've been out of the Cellular Biz for ~2 years, I think I can offer some tips that will reduce to just a few the number of "unknowns" you'd have to address during some trial-and-error experiments. When you mentioned not using OnStar beyond Year 1, that made this answer worth posting since it's now "just" a connectivity issue. I'm trying to address the general topic; not just Passat specifics...

Custom Software & Protocol aside - you won't have to deal with those issues - I can mention these features unique to all the Hands Free Kits I've ever dealt with. BT kits use these same hard-wired protocols.

1. All Car Kits - including the Nokia - pull a MUTE line from +5 Volts down to Signal Ground during Call activity. That line then switches over the HU function to accept the typical 0.7 Volt "line level" signal - a type of AUX in, really - from the Car Kit and plays back that Call Audio signal through one or more front Speakers.

The trick will be to find that MUTE line and put a Voltmeter on it to confirm the function thereof. You'll then want to disconnect that MUTE line from the OnStar circuitry and patch the line to the Car Kit MUTE line "output" instead.

2. Mics are 1 of 2 types: Amplified or non-amplified output. There's not a great difference between the output level Voltages of them, but there's a more vexing issue on top of this distinction.

Some Mics with an "unbalanced" Output have a "+" and a "-" output. The "+" is the inner conductor of a small coaxial-type cable, and the "-", or Signal Ground, is the braided outside lead of the small cable. For better rejection of Vehicle Signal Noise, other newer Mics have balanced, or Differential Outputs. In this configuration, the two leads have the Mic Output signal as a variation between them, and both have Voltage potential above Signal Ground.

You can typically plug the Mic you now have into the Nokia Car Kit because any and all Mics connect into an isolating first stage Op Amp, and nothing will "blow up". Unbalanced Line Output Mic circuits typically use a submini Phone Jack; smaller diameter than what's on a Portable CD Player, but of the same style. Replacing a Mic is no big deal, BTW.

If required, a new, compatible Aftermarket Mic can be cut out of the enclosure - which is usually the profile of an oversized Lady Bug - and fit into the overhead Mic location. This "bare" Mic mounting, which may have a small Circuit Board, is a typical OEM implementation that you can duplicate. So, don't let Mic enclosure "size" put you off this Project.

The usual disclaimers apply in this on line advice, of course!

3. Once triggered by the BT MUTE line, the HU will continue to switch over and play back Call Audio through the Speakers. This switch over function may be an external, in-line "black box" that will have the MUTE and Call Audio Output lines connected into it, while having the front Speaker wires connect in and out of it. Chase down the front Speaker wires after they leave the HU to see if this is the case. You can shove 2 straight pins through suspected wires and connect Voltmeter lead clips while turning up the HU to then see if Speaker signal goes away during Call activity, etc.. Hopefully, though, detailed HU Wiring info is on line so that you skip the hard-core Reverse Engineering exercise. See a good overview here:

http://www.autoleads.co.uk

If all these functions are integrated into the OEM HU, that will become obvious with investigation, too. After-the-HU Speaker switching, via an outboard "black box", is very standardized within the Industry and is how all Aftermarket installs of Car Kits are made to appear OEM to the User.

You may find that the MUTE line "splits" and connects to both a front Speaker switching "black box" and into the HU [to switch it over to the AUX line input during Call activity]. That type of split MUTE connection is OK for you to make with your BT Kit, too. I didn't work the OnStar Account, so mass-produced HUs they use may make this entire answer rubbish! But, you can at least chase down what the starting situation is...

Just as Wiring Harnesses have in them functionality - like Heated Seats - that may not exist in every Vehicle, your HU may have all this Call functionality built-in at lower cost to the Vehicle Manufacturer than if an external "black box" were installed. This Call playback-HU functionality may then be enabled only when OnStar is ordered.

HTH... Good Luck!
 

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westerdave I found mine uses Verizon Wireless actually, after "dialing" the wrong number.

I'm very interested in tapping into this system as well. Not with bluetooth, since I have an LG phone, but I'd be happy enough with a wire down my windshield that I can mount my phone on the dash, plugged in. But getting it tied into using the microphone and, more importantly, headunit, will be tough I think.
 

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OK folks I'll tell you what I know and don't know.

Firstly, if the On-star thing is just an add-on to the radio, it shouldn't be much to remove. If the radio is still the same double Din unit as the 2003 models, it includes a mute line and telephone speaker inputs. You just need to connect up. If you pull the headunit, you will see the wiring diagram.
 
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