GM Lan Single Wire CAN Bus Sniffing

[Morris70]

Just thinking about how to build a GMLAN module for the h/u RGB input - it probably wouldn't need much in terms of hardware, maybe a 28 pin PIC18F2480 with the CAN protocol engine built in, a TH8056 or similar single wire CAN transceiver, 78L05 5v regulator, XTAL etc. Parts all up would probably be around $10-20ish
I bet that is about all you get in those $400 modules for disabling the VIM or enabling the camera input...

[TazzI]

Just thinking about how to build a GMLAN module for the h/u RGB input - it probably wouldn't need much in terms of hardware, maybe a 28 pin PIC18F2480 with the CAN protocol engine built in, a TH8056 or similar single wire CAN transceiver, 78L05 5v regulator, XTAL etc. Parts all up would probably be around $10-20ish
I bet that is about all you get in those $400 modules for disabling the VIN or enabling the camera input...

Ill take a picture of the components in the module my mate used to enable the vin and reverse camera when I eventually get around to driving out woop woop to get it off him. Can probably have a glimpse at it in person if you want. Since after that its heading off to doubledip to have a looksy.

My first thought on it was that it stores the vin of the car in the module.... could we be luck enough for there to be an eeprom to rewrite?

[Morris70]

That model PIC has 16k of flash memory and a 256 byte internal eeprom, and theoretically the contents could be read from a programmer.They can also have protection bits set so it can't be read externally...

If the designers were smart, they will have implemented the code protection features to stop people hacking the things

[L18]

Hello!
I use a bit different device to sniff that GMLan, Microchips USB CAN analyzer.
I can receive the data ok, but I'm having difficulties to compare that data to yours, or to GMLan_bible.
Could somebody maybe help me know if ID that is on microchips program, is the same as Arb. ID?
The program has these fields: ID, DLC, DATA0, DATA1, DATA2, DATA3, DATA4, DATA5, DATA6, DATA7.
I've managed to adjust the volume through CANbus, with sending this: 175 08 00 00 00 00 01 00 01 volume up and 175 08 00 00 00 00 02 00 1F volume down.
Can somebody please explain what that means?
It looks so different than the codes you've posted here...sorry if I explained myself poorly, english isn't my native language.

[Morris70]

Went and ordered a Uno and proto shield from RS, and built a CAN shield based on the Sparkfun design.
Didn't bother installing the micro sd slot and was just going to monitor things from the serial console.
I'm now thinking logging LSCAN data from the bus to the SD card might be the way to go - is anyone using the SD card slot for logging ?

Arduino.JPG

[jezzab]

Hello!
I use a bit different device to sniff that GMLan, Microchips USB CAN analyzer.
I can receive the data ok, but I'm having difficulties to compare that data to yours, or to GMLan_bible.
Could somebody maybe help me know if ID that is on microchips program, is the same as Arb. ID?
The program has these fields: ID, DLC, DATA0, DATA1, DATA2, DATA3, DATA4, DATA5, DATA6, DATA7.
I've managed to adjust the volume through CANbus, with sending this: 175 08 00 00 00 00 01 00 01 volume up and 175 08 00 00 00 00 02 00 1F volume down.
Can somebody please explain what that means?
It looks so different than the codes you've posted here...sorry if I explained myself poorly, english isn't my native language.

Looks like an 11bit CAN packet. But the $175 address doesn't match the standards. Can you set some flags and make it read the 29bit packets?

[jayman488]

Hey everyone, first post here. I'm thinking of getting a SparkFun shield but I have a question about connecting it. Is it necessary to connect all 9 of the DB9 pins to the OBDII port? Or is the pin 1 can line enough by itself? I ask because I have a 2006 Cadillac CTS, and the radio harness has a couple of wires labeled "Class 2 Serial Data". I was wondering if I could just hook that up to CAN-H on the SparkFun shield, and leave the OBDII port open for other purposes.

[beetlepart]

My first post, trying to use yet another mbed based project I found at http://mbed.org/users/Just4pLeisure/not ... t4trionic/ to marry a replacement ECU in a Saab 9-3ss by rewriting VIN and immobiliser (VIM?) codes.

My quest to locate a copy of GMW3110 has brought me here. I have already got the SPS programmers reference manual (not sure of the etiquette about posting so PM me if you want a copy).

Have downloaded copy of GMW3110 posted by abodah on page 18 but adobe reader can't open it, and dropbox copy foxdie and jezzab reference has been deleted. Would appreciate pointers to where I could get a copy.

Cheers

[velj]

never looked into this stuff befor and now i have, its gotten me excited, even tho im like years to later haha,
looking into getting the can bus shield off sparkfun, but dont no what one to get, there is either this one or there is this kit, from what i read it basicly does the same, what should i get? thanks guys.
also what else do i need to get apart from the obd2 cable
https://www.sparkfun.com/products/10769 or
https://www.sparkfun.com/products/10039
also found this i like the idea of the lcd
http://www.ebay.com.au/itm/130937500143 ... 1438.l2649

hopefully by doing this il be able to make a add on so that i can have my phone connect to my headunit wirelessly stream music to it and so on also to use the steering wheel controls ect,

thanks
Daniel

[tiburon]

I hate to be the newbie asking the dumb questions, but I bought the SparkFun can bus shield and I'm trying to get it setup to work on the gmlan. I understand that Pin 1 needs to go to can-h and can-L needs to go to ground. To get pin 1 to can-h are people just modifying a OBD-II to DB9 cable? Do all other wires stay in place or is just Pin 1 to can-h the only thing left hooked up?

I'm gathering that I hook up can-l and ground where the 5v/GND/CAN H/CAN L pins are in a row by jumping CAN L over to GND. Assuming this is correct does the board still just attach to the Arduino (or in my case a Netduino) buy "stacking it on top"? It just seems like I am by passing a bulk of the shield buy going directory to those four pins so I wan't sure if buy doing that I was also needing to hook the shield up differently to the Netduino.

Also is the code for communication on the gmlan the same as communication on the standard unmodified odb II connection? I'm wondering if I should get things working in non-gmlan with the code and then switch over the hardware so that I know my code is working first.

Thanks for the help.