: class 2 bus?

07-22-11, 10:42 PM
I read in here some where about a product called Galaxy 1000, which uses blue tooth technology and the existing on star equipment. I tracked Fred down and bought a Galaxy for my 06 XLR It does not go on. I need to know if the xlR has a class 2 bus like the corvette. Can any body help. I confess I know not of what I speak, But I was told to ask. If anybody knows, it is some one here.

07-23-11, 03:34 AM
Hi Frank!

Yes, the XLR has a Class 2 (low speed) bus. It also has a GMLAN (High Speed) bus, which needs a CANdi module (with a Tech 2) to communicate. Has anyone sucessfully integrated a Galaxy 1000 with the XLR? The dual bus may be an issue.


07-23-11, 08:46 PM
Thanks for the info. I will relay it to fred at Galaxy. I also own A blue star by co star. It comes close, but is not really usable. I'll let you know if Fred is able to get this to work. He is convinced it should work if the car is a class 2 . What else can you tell me about the double bus, High speed ,low speed, that might help?

07-23-11, 09:02 PM
Greetings Frank,

The GMLAN modules connected to the high speed serial bus transmit critical, time-sensitive info like Stabilitrac, Adaptive Cruise Control, and Braking operating information and commands. The slower Class 2 bus is used for lower-priority infotainment, HVAC, etc.

The Class 2 bus operates over a single wire at 10.4 kBps and uses variable pulse width modulation to carry the data. The bus is inactive @ 7vdc. With the vehicle operating, each module places a Status of Health message on the bus every two seconds. If the module fails to send the expected message, other modules that communicate with it will set a fault code. This loss of data code doesn't mean the module that sends it is bad; it's just letting the system know it's lonely and something is amiss. The data link connector under the steering column is a sixteen pin. B+ is on pin 16, power supply gnd is on pin 4, and a clean system gnd is on pin 5. Class 2 serial data can be found on pin 2.

What else would you like to know?


07-24-11, 10:43 AM
Thank you CC,
I have no clue what else I / they need to know. Might be better if Fred could talk to you direct. You seem to know the right type of data. I have forwarded your reply, and this note, to him.
There is a detailed review of his product, ie. Galaxy 1000, under blue tooth, onstar and probably if you search Galaxy 1000, it will come up. There his contact info is listed.
Since you also own a CTS, Let me ask you this: We know this galaxy works VERY well in the CTS. How does the CTS differ from the XLR in terms of this bus??

07-24-11, 01:36 PM

CTS uses the Class 2 network exclusively and does not have a high-speed GMLAN. It uses the Class 2 serial bus to communicate between the VCIM (Vehicle Communications Interface Module) and the Radio. CTS is similar in that it requires a CANdi module for communications to the Tech 2.

XLR implements both Class 2 and GMLAN in it's VCIM to communicate with the vehicle's systems. Onstar uses both busses to communicate with the vehicle to run operate different features (horn, doors, and exterior lights.)

I know little about the Galaxy 1000 (since it's never been an XLR product) other than what I just checked out on their website, --noticing the XLR was not one of their presently supported vehicles. The XLR is a PITA to interface with, whether it's an entertainment system or iPod interface due to it's integrated dual-network architecture. It is very similar to the C6 corvette though. (Similar doesn't necessarilly mean it will work out -just like human-monkey hybrids.)

This is why you'll see posts here from experienced gearheads who talk about dropping a different engine into the XLR as if it were plug and play with a few tuner tweaks to the system, without any in-depth knowledge of the complexity of the vehicle's communications architecture and protocol. (GM proprietary.) It's like nothing that came before it, and was a technology testbed for the Cadillacs that have come after it -though none are as thoroughly integrated as the XLR still. Does the new CTS-V coupe have Adaptive Cruise Control? Nope! There's no reason why it couldn't, but the XLR had this feature --along with many others still trickling down, eight years ago! (First XLRs came out in 2003 for Nieman Marcus.)

While an engine can be installed in a vehicle physically, interfacing to the XLR withouit losing functionality with it's integrated systems is not economically viable. That's why it's all talk, no action. Less complex systems fare little better --as you're experiencing now. Not impossible, just hard.


04-01-12, 09:14 AM
I thought I should up date this thread with out come of the conversion from onstar to a bluetooth capable system. In the end it was Chris at Costar who has the knowledge, software and equipment to do the job. I am very happy with the Blue star unit he builds and sells. Chris spent a lot of time helping me. It was a simple adjustment to the gain level in the unit that made it work. He can explain how to do it in an email. This is not my everyday car and so I am responsible for the slow fix, as it took a long time in between discussions for me to try things out. (I travel a lot)
If you are interested in converting the onstar system you are not using ( which costs $18.00 a month plus phone charge) to a no cost hands free system that works off your cell phone; Blue star is the way to go.
You can find the company here <http://www.costartech.com/ > and /or you can read the installation manual here < http://www.costartech.com/pb/products/datasheets/BlueStar%202010%20manual%20rev%202.0.pdf >
Just for the record I am not connected with the company.

04-02-12, 11:31 PM
GM has a few architectures

Older cars like the XLR and Corvette use a combination of GMLAN and Class 2 starting in 2004/5 (for Engine, ABS, Ride Control, OnStar, and Auto Transmission). Before that cars used Class 2 exclusively and the UART bus before then.

Since 2004 GM has had GMLAN which actually is 3 differnet types:

11-bit GMLAN Common Architecture that you see on early mid-sizers like the 2004 Malibu and the 2005 G6.
29-bit GMLAN Common Architecture that you see on the 2008 CTS, and 2009 Traverse and 2007 Silverado
29-bit GMLAN Global A Architecture that you see on LaCrosse, Cruze, Volt, and all new cars introduced on new platforms after 2010.

My GTO uses UART except for the LS2 engine and the ABS module which are GMLAN.