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Last night I took the OnStar unit out of my 2003 9-3 Arc from the trunk located under the deck in between the 6X9 speakers. At the website at http://members.cox.net/onstar/, the procedure explains how to tap into an OnStar GPS receiver using an RS232 cable that can later be plugged into a laptop/pc/pocket pc.

The problem I'm having is that the OnStar unit shown and modified on that website is different from what's in my Saab 9-3, so I'm not sure how to wire the RS232 cable to the unit. The unit in my 9-3 is labeled as a device manufactured by Delphi Delco Electronics System, Delco part number 12240549. The label that I'm speaking of is shown below:

 

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On the second picture, you'll see that I took the OnStar unit apart. The GPS component of the OnStar unit has a metallic shield/casing over it that is soldered onto the board, and I was not able to detach it because I didn't have the equipment at the time (but i'll try to unsolder it at a later time and i'll post the pics).

 

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The fourth picture shows the GPS cable (not the antenna) connected to the pcb board with a connector. I believe I could pick up the GPS signal from this cable or from the pins of the connector on the other side of the board. All I need is the details on how to connect the RS232 connector to these wires and that would make my day. Anyone out there know anything about this?

 

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I think you might be the first one to do this kind of surgery on our OnStar unit, believe it or not. If you are able to pull something off with this, congratulations are in order. :)
 

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Discussion Starter · #7 ·
Thanks for that info Viscouse. I just sent a PM to gh0ztt who said he had opened up the OnStar unit as well in the thread you created. Maybe he eventually got the pinout information of the GPS connector.

I took another look at that the Saab 9-3 OnStar unit's GPS component connector and I noticed that it has 10 wires on it, just like the one on the Avalanche's unit shown at the http://openminds.net/onstar web site. The only difference is that the connector on the Saab's unit is a single row connector, and the one on the Avalanche unit is a double row connector. It's possible that the signals are pin for pin the same on both connectors. But, that's what we need to confirm in order to make use of this mod. IF the pinouts are the same pin for pin, then the following chart would be correct:

THE FOLLOWING INFORMATION IS NOT CONFIRMED FOR SAAB, DON'T USE UNTIL CONFIRMED

PIN SIGNAL Description RLC-1 TTL Converter

1 Battery Backup Power
2 +5V PWR Main Power Vcc/White
3 Ground Ground
4 VPP Flash Memory Programming
5 RTCM In DGPS Correction Input
6 1PPS 1 Pulse Per Second Signal
7 1 PPS RTN 1 Pulse Per Second
8 TTL TXD Transmit Logic 5V Data Out/Red
9 TTL RXD Receive Logic 5V Data In/Green
10 TTL RTN TTL Signal Ground Power and Signal Ground
(this information was used in reference to information at http://openminds.net/onstar)

Also, if the connectors are pin for pin the same, we still need to determine which pin on the Saab's connector is number 1.
 

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If you do tap into OnStar with a 232 cable....where do you plan to route the 232 cable?

If to be interfaced with laptop or PDA, surely you will want 232 cable routed to the front of the car, perhaps center console?

232 connector is fairly bulky...how do you plan to route the cable, and "hide" the connector so its not an eyesore in your car when its not being used to interface to other equipment?

Do you know if you have digital or analog OnStar box?

It would be nice if you could use CAT5 UTP network cable to interface out of OnStar to Laptop (via ethernet)

RS232 is kinda old-school IMO - why it would be needed in a car that has a fiberoptic network preinstalled is beyond me - must be an OnStar thing (RS232 requirement)
 

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Energy_AZ, this is where things get really neat. I didn't want to mention this yet because I wanted/want to concentrate first on getting the pinout for the connector, but since you asked I might as well go there.

I don't plan to run any wires through the car at all. I don't know if this has been tried or planned before, but I was planning on purchasing an RS232 to Bluetooth converter at http://www.aircable.net/ and plugging it into the end of the RS232 cable that was moded into the OnStar unit. I have an HP Ipaq 1940 that has built in bluetooth already that should be able to pickup the Bluetooth transmitted GPS signal. The bluetooth converter is only $50 bucks.

Here's a pic of the AIRCableSerial-Female device:


Here's some techincal facts we may need to know:
- Dimensions: 56 X 37 X 16 mm
- Power Consumption: 50ma
- This device can be powered through pin 9 of the DB9 connector (DC 4-10V).

If anyone knows or sees a potential problem using this device, please tell. Otherwise, let's concentrate on determining what the pin signals are on the GPS component connector.
 

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Putting Bluetooth to send the GPS data from the RS-232 is a great idea. However, you need to make sure if the Bluetooth converter is already level-shifted. From what I can tell at the aircable website, it is already level-shifted which means that you need to level-shift your GPS serial output to match, otherwise you will toast the GPS receiver.

If you can remove the GPS receiver from the OnStar unit and pop open the metal can enclosing the receiver circuit board, I may be able to help you figure out what the pinouts are. All you need is to find the ground, TX and RX signal of the GPS receiver (and maybe +5V to power your Bluetooth sender) and you are all set.
 

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epsilon93, thanks so much for your input. I definetely don't want to fry my board, so if you could help me prevent doing that, that would be great! :cheesy: When I read your post, I started working on it right away.

epsilon93, when you mentioned level shifting the signal, does that mean increasing the voltage level? On the http://openminds.net/onstar/ web site, they mention using a RLC-1 3v/5v RS232 Level Converter. Is that all that we would need and would this prevent the problem that you are talking about?

When I took the OnStar unit apart again, I noticed that the connector that I was talking about tapping into is a surface mount connector, which means we can't tap into it from the other side of the board through its would be pins. epsilon93, how would you recommend tapping into it knowing this?

Here are the pictures of the dissassembled GPS receiver component of the OnStar unit. Notice that it has a Sony chip on the top side of the board. (epsilon93, if you need bigger pics i got them. I had to shrink the size for the forum):

GPS Receiver Board - Top Side


GPS Receiver Board - Bottom Side
 

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wow, that would be great. I have a very big powerbook G4 but it does have bluetooth in it! would normal GPS software pickup the onstar GPS reciver? This would be great for long trips
 

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No offense but isnt this a lot of money/time trying to do something that you could just do by buying a 100 dollar bluetooth GPS receiver? Why not just do that?
 

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Discussion Starter · #15 ·
BlackSaab, thanks for that information. I was looking all over for that and couldn't find it. That will definetely be helpful in figuring this mod out.

Topspin14, this mod shouldn't cost a lot of money or time once we have a procedure to do it. I haven't found a cheap bluetooth GPS receiver, but I could a give you a couple, maybe a few reasons why the mod would be better.

Reasons why the OnStar Bluetooth GPS Mod would be better than a standalone Bluetooth GPS Receiver:
1. No batteries to replace. The device will be constantly powered.
2. No clutter. With the standalone bluetooth GPS receiver, you have to place it in a location where you will get a satellite signal, like the windshield. The windows in the SAAB have a metallic coating on it that may make it difficult to get satellite reception through it.
3. Great GPS Reception. The OnStar Bluetooth GPS Mod will utilize the car's OnStar antenna to pickup the satellite signal.
4. Reduce Redundancy. Your Saab already has a GPS receiver in the car (if u have onstar), why not use its potential. Plus once you make the mod, you can tell people your car has bluetooth built into it. :D
5. In my experience, Cheaper. I've tried finding a cheap bluetooth GPS Receiver, but haven't had any luck with it. The mod should cost well below $100. I'll post full details on the cost once we have a procedure for the mod.

ek03, I don't know much about the Apple OS and what navigation software is offered for it, but I'm sure there is something out there for it. Just make sure that the software supports bluetooth GPS reception.
 

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Hi Mitch,

Level shifting in this case means converting the serial logic signals to RS-232 compatible signals.

OK, you've done a good job here taking the GPS receiver module out of it's can. The module looks like a Sony receiver module model GXB3000 but I cannot seem to be able to locate the datasheet for this module so I can't be sure. However, you can check the GXB2000 spec here;

http://products.sel.sony.com/semi/PDF/GXB2000.pdf

If you look at the pinouts on page 7, the GXB2000 has the exact same number of pins as what you have in yours. I am pretty sure that the pinouts are identical for the GXB3000. If you have a scope you can determine this. You can easily check the Vcc and Ground pins using a multimeter.

As for tapping the signals, if your soldering skills are good, you can still solder on the pins of the connector. If not, you can just splice the wires for the signals you need.

I am sorry I cannot be more exact. I have worked with the GXB1000 and GXB2000 GPS modules before and they are direct pin to pin compatible so I am pretty sure GXB3000 is the same. Unfortunately there is no way I can know for sure unless I have seen the GXB3000 receiver module first hand.

BTW, the GXB3000 uses the CXD2932 chip. :wink: The CXD2931 is the older version which is used in the GXB2000 module.

Hope that helps.

eps
 

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Discussion Starter · #17 ·
epsilon93, thanks for that information! I should be ready to do this mod soon. I just have two more questions to ask.

To power the aircable, it says I can power it through pin 9 of the DB9 connector with 4 to 10 volts and its power consumption is 50 milliamps. Do you think it would be ok to split the 5 volt vcc signal of the RS232 cable to power up the aircable device? Would it be too much juice to take from the 5 volt supplied from the connector on the PCB board? If it is, where should I get that juice from?

Second, I wasn't sure if you confirmed or not that using the TTL to RS232 cable was sufficient for this mod to prevent the OnStar board from cooking. Is that all that I would need?
 

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So I'm dragging this up fromthe dead in an attempt to finish it...
This outlines some of the differences between GXB2000 & GXB3000: http://products.sel.sony.com/semi/PDF/SS_GPS.pdf

Assuming 2000 & 3000 are the same except for generational touch-ups, here is the pinout:
1 VCC Main power supply
2 RESET Reset input for initializing the reception unit.
3 TXD0 Measured data output.
4 RXD0 Command input.
5 RXD1 D-GPS data input.
6 MODE Communication format switching pin. (L = Sony, H = NMEA0183)
7 NC No connection.
8 +BU Power supply for backup.
9 NC Fixed H level.
10 GND Ground

VCC should be 5V. So assuming the pins are arranged sequentially (1-10), using a voltmeter and the car as ground, one side of the conenctor should get 5V, the other nothing.
The hard part is that it will have to be running, connected to the car while I do these tests. :eek:
 

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Vis,

You can still pullout the Onstar unit. Power it up using a 12V batt via the pins as outlined on the sticker on the unit. That way you can tap into the pins and test. Arrrgggghhhhh.... wish I can help you with it. Probably wouldn't take me long to hook it up. I have some Bluetooth modules here that will do the job nicely :D
 

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Thought I'd give a post-mortem on the surgery I performed today.
I removed the Onstar box & tried to verify the pins per the info we've dug up so far.

Short version: mixed results, but not what I expected.

Useful info: The car WILL start & run without the box. The only notable thing missing being the audio system. SID even worked. It told me Onstar was acting screwy & I should contact my dealer. :cheesy:

Long version: So I had a PIA time trying to deal with those tiny wires. The picture is blown up pretty nicely, but the white wires are about the size of hairs.
The connector does have pin numbers on it, which is a bonus. You need to be a pixie to read them though.
Enough whining. I tried to power it with an old AT computer supply putting out 11.9V. I was having no luck, but I think it was because in my infinite wisdom I had the connector unplugged from the board. That didn't make sense. After about 15 more iterations, I said screw it, and put it back in the car & let the car power it. I then measured (with the cable plugged in).
Between pin 1 & 10: nothing (like 100mV)
Between 2 & 10: 3.3V

This exersize was mainly to verify pinout. In this pursuit the experiment failed (pin 2 is reset, which should not have 3.3V).

But it is slightly helpful.
For me to continue testing, I have 2 small obstacles:
1: I have no idea if I did something wrong & fried the box, thereby nullifying further validations. (I don't subscribe to onstar)
2: I am having a real hard time getting to the contacts. I'm using a pin to the surface mount contact. It's about 1/5 of a square mm. I'll just throw this out there, if anyone is from Delphi & can get that connector, we'll be in business. Until then I will have to splice the cable, but am extremely scared because it is on a scale so small I don't think I can strip it.

If anyone has any brainstorms tomorrow I'll try em out.

EDIT: after reading the spec, it is possible that pin2 (reset) have a constant voltage of 3.3V, so that's good. Why didn't pin1 have 5V though?
 
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