GM Lan Single Wire CAN Bus Sniffing

[jezzab]

Put it this way, I can fire up my busted ass old S1 radio on the bench with NOTHING CAN related plugged into it and use it. Just power....

[foxdie]

I think what Jez is trying to say here is yes it can be done and has been multiple times in the past. Your local GM Dealer just confirmed his / her limited competence on the matter. That or they were just trying to deter you because, well, it's taking money out of their pocket in their eyes

There's a lot can be done with the series 1 and 2 head units. There's 3 ways to approach what you're doing;

1. Change the VIN in the head unit
2. Trick the head unit into thinking its still fitted in the old car by spoofing data
3. Completely disable VIN checking

All 3 options are achievable, several of us have already have with time and patience. Its not information we're gonna just give out freely though, not because we're mean but because we all stand by the principle of give a man a fish.

What we're happy to do though is help steer you on your journey. I suggest you start by familiarising yourself with GMLAN doc GMW3110, its an incredibly insightful but daunting read and separates those with dedication and passion from those who are just in it for a quick buck. Even 12 months on, I still find myself referring to it for new information.

The more you demonstrate you know and the more you assist the community, the more doors open

[acca]

Hello everyone

I have an Opel Astra J , produced by GM.

I'd like to use an arduino board with sparkfun can shield i, order to read steering commands

Could you please help me, i'd like to know if i must tie CAN_L to ground and connect CAN_H to the single wire CAN.

Wich pins have i to use on the obd connector ?

Just to be sure beefore breaking my car !

thank you very much
sorry for my poor english

[acca]

Hi again

I managed to communicate with my car and faound that the message 10 43 80 40 01 means VOL+

I found it by comparing a dump of CAN messages with and without pressing the Steering Wheel buttons.

It's not according to the GMLan Bible, right ?

Now i'd like to manage to write to the LCD screen wich is above the Radio, but i don't know how to guess the LCD header

Did someone managed to do that ?

Thanks

[jezzab]

Look for the text being sent to the radio in ascii hex. You will find the GMLAN bible stuff is based on the Holden VE platform and its variants like Vauxhall and Pontiac G8

[acca]

Yes i did it, but can't find text by calculating CHAR(HEXDEC(bytemessage))
I use the code from this page : https://github.com/Afterglow/arduino-gmlan
The output is in attachment, there are two worsheets, one without pressing a button, the other recorded when pressing a button.

I have to admit that i don't understand CAN parameters in the code. Maybe i don't listen to good messages ?

Regards

[jezzab]

Only ASCII text i see is your VIN (0LPD6EG8C1012082). Are you SURE the radio and the display above it are actually separate modules and have their own CAN ID's and is not just a external display for the radio???

[acca]

Yes because i have a dension Gateway pro box (to read mp3 from an usb stick) wich use CAN bus to read steering wheel commands and wich is able to write to the lcd screen

[jezzab]

well plug it in and log it when you start playing a MP3. Does it display the track name? When you press volume up or down what is actually displayed on the screen?

[acca]

Hi
Here is another try

I was playing a mp3 using cd player, the title is on the screen then i changed displayer informations (album, artist ...)

maybe the arduino code is filtering the message ?

Can someone explain this par of code please ?

Code: Select all

  flags = mcp2515_read_register(CANINTF);
  if ((flags & 0x01) == 0x01) {
    renderMsg(0x61);
    // Clear the message flag..
    mcp2515_modifyRegister(CANINTF, 0x01, 0x00); 
  }

  if ((flags & 0x02) == 0x02) {
    renderMsg(0x71);
    // Clear the message flag..
    mcp2515_modifyRegister(CANINTF, 0x02, 0x00); 
  }