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Discussion Starter · #1 ·
anyone have access to or able to provide me with some information about the DIC?

i have realized that it is possible to interpret the voltages/signals coming out of a harness to the stock radio, or else the aftermarket dash with DIC retained would not be possible.

my goal is to do the same thing. preferably just interpreting the signals into a custom adapter that would connect to a computer. i would then write up a program to interpret the signals to be displayed on an LCD that would replace the factory headunit.

anyone have any access to this type of info?

anyone have any ideas for a workaround?
 

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Radio doesn't receive any voltages/signals that relate to the driver info center functions. It only acts an a display device for text display message sent via serial data link from BCM on a single wire. That is why is was likely fairly easy for a few aftermarket companies to already create the type of display you are talking about. There have been other posts on those products elsewhere.

If you want more details use Google to search for keyword GMLAN
 

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Discussion Starter · #3 ·
i'm going to post a few links...

http://www.vector-cantech.com/index.html?../oem?oem_gm.html
this one has downloads, apparantly from the company that created the GMLAN for GM.

http://www.gmtcny.com/lan.htm
seems to explain some things...

http://www.intrepidcs.com/neovi/main.htm
looks like an overly costly solution for implementing a display into my own program...

http://elsmar.com/Forums/showthread.php?t=4917&highlight=malibu
seems to be these guys have some potentially helpfull info, but i've got no clue...

http://www.ime-actia.de/web_can/pc_inter/xs_family.htm
another product that seems like it does more than i need.

i assume the data is transmitted via hexadecimal from what i've gathered. can you confirm?
 

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Discussion Starter · #4 ·
ok, what i've got so far is that it sends the signal to the Radio via a single wire (per your usually reliable info ;) ).

i'll assume the buttons on the radio are:

1) to rotate between what is displayed; or

2) to tell the GMLAN to send another signal.

and

1) to tell the GMLAN that you want english or metric; and

2) to tell the GMLAN to reset the database.


so in theory, i need my program to interpret the signal for display to:

1) display ALL data being transmitted, which would require me to have the program know what data is for what,

2) be able to send the signal to reset whatever needs to be reset (oil, mileage, etc.) and

3) send the signal to rotate between english/metric

or

1) display the data currently being sent and be able to rotate between what's being sent,

2) be able to reset whatever is currently displayed, and

and

3) send the signal to rotate between english/metric



do you happen to know if ALL communications to/from the GMLAN carry on the one wire, or is there another to send signals back (or two, one to reset, one to change metric/english), and is the radio responsible for interpreting the data being displayed, or does the GMLAN send it all, and the radio is configured to display what the user selects (i.e., if i used an LCD character display with 4 lines, could it display it all, or will it still have to communicate to the GMLAN when it wants new info?).

any kind of bone you could throw me can help. i can find help to do the hardware aspect of it, but it seems that finding any real info on the signals requires cash...
 

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Discussion Starter · #5 ·
i just want to add (for personal thought) that this could be usefull in keeping a database of what mileage you've been averaging while still being able to reset it for each trip. would be simple enough to keep a running tally, and a lifetime average once i'm able to read the data.

too bad i didn't go to school for computer science...
 

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Well - you certainly found some good sites ;). Some of their products are kind of expensive though.

Give me a little time to figure out what I might be able to post back.

This site is from the guys that actually invented CAN from which GMLAN is based Bosch. This describes the 2-wire high speed bus which is also in a G6 but the radio runs on a different single-wire bus (slower speed).

BTW did you buy a G6? I know you were looking at a 4 cylinder model

EDIT
You are correct that activation of the radio switches for Driver Info Center are just sent to the BCM to give it basic commands: Info, Menu and Reset. The BCM is in control of the Driver Info Center and it keeps track of what needs to be displayed. There is only that one wire which both the radio and BCM communicate over - each packages the data they send out to rest of vehicle. This same data link is used for many of the electronic modules in vehicle - it isn't just dedicated to the radio and BCM.

That is about all I can say :)
 

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Discussion Starter · #7 ·
e2helper said:
Well - you certainly found some good sites ;). Some of their products are kind of expensive though.

Give me a little time to figure out what I might be able to post back.

This site is from the guys that actually invented CAN from which GMLAN is based Bosch. This describes the 2-wire high speed bus which is also in a G6 but the radio runs on a different single-wire bus (slower speed).

BTW did you buy a G6? I know you were looking at a 4 cylinder model

EDIT
You are correct that activation of the radio switches for Driver Info Center are just sent to the BCM to give it basic commands: Info, Menu and Reset. The BCM is in control of the Driver Info Center and it keeps track of what needs to be displayed. There is only that one wire which both the radio and BCM communicate over - each packages the data they send out to rest of vehicle. This same data link is used for many of the electronic modules in vehicle - it isn't just dedicated to the radio and BCM.

That is about all I can say :)
picking up my granite metallic 1SV G6 on monday!

ok, so what i need to figure out is:

1) how to identify what is being sent to the DIC (given that one wire is used to send to other modules) and from what's being sent to the DIC figure out what i'm looking at,

2) what gets sent back to the BCM to clear the data, and

3) what signal tells the BCM that i want the next item to be displayed.


not to mention that i need to also know how to tell it i want metric or english.


i'm going to find out what i can, and think this through in more detail, maybe draw up some schematics for what i need. i know if i can interpret the data, i could hack up some hardware that will communicate with the carputer via serial port.

also, i can't get this info via OBD-II can I? i assume not, but it could be an easier solution.

i think it may be easier to just fab up a mount for my LCD below the HVAC controls, as it's main function will be as an MP3 jukebox, GPS to follow. ahhhh the fun of it all. one day i'll come on here saying i got something displayed, and it's not right, lol...

:bandit:
 

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I thought I should mention that since this wire is part of one of the vehicle's main data busses, that if you were to do anything to disrupt communication between modules you would cause problems like a no start.

The OBD-II bus used for emission diagnostics is the other data bus in vehicle which operates at a much higher speed (20x faster?) and is twisted pair wire. The radio doesn't participate on that data bus.

As far as identifying individual data on the bus; you likely wouldn't be able to do this without special tools and more knowledge specific to GMLAN.

FYI - Even the Tech 2 tool used by dealerships doesn't display normal communications between modules. It only uses special diagnostic data
 

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Discussion Starter · #9 ·
e2helper said:
I thought I should mention that since this wire is part of one of the vehicle's main data busses, that if you were to do anything to disrupt communication between modules you would cause problems like a no start.

The OBD-II bus used for emission diagnostics is the other data bus in vehicle which operates at a much higher speed (20x faster?) and is twisted pair wire. The radio doesn't participate on that data bus.

As far as identifying individual data on the bus; you likely wouldn't be able to do this without special tools and more knowledge specific to GMLAN.

FYI - Even the Tech 2 tool used by dealerships doesn't display normal communications between modules. It only uses special diagnostic data
so i'm better off saving up for something like this in order to input data to my program for display?

do you know of any issues where having a tool like this plugged in all the time could cause problems?

EDIT: also, this would connect to a totally seperate connection than the OBD port, correct?
 
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