I have ordered a Single Wire CAN Bus adaptor from GTOSoft LLC...
This adaptor is a modified ELM327 OBDII Adaptor, to work with the GM Slow LAN Can Bus.
http://www.gtosoft.com/?p=81
I know the information on how to make one of these yourself is up on the website page that I linked to,
to be honest, the price that these units sell for, I don't think its worth the time to try and source the parts,
and trying to build one yourself...
Anyway, this thread is to try and work out a couple of things,
1) Work out what the Sat-Nav GM Lan Gateway module sends on the Bus, to enable the Colour LCD VGA Input.
This is the highest priority hack that we are trying to work out at this point in time.
2) Work out what other information the Sat Nav system sends on the BUS (Street Name, Direction Arrows, etc).
This is kind of Meh, as I dont think any aftermarket Sat Nav systems send this information out on a serial port, or any other data port which could be integrated in to the VE models like the Factory Sat Nav units.
However, this could be handy for in car PC stuff ????
3) Work out the Park Assist data (How to enable the Park Assist screen on the Colour LCD Screen).
Again, kind of Meh, as once we have this data, we might be able to do a proper park assist project with an arduino using factory Ultrasonic sensors, or via an in car PC ????
4) Work out anything else that might seem funky at the time.
Maybe some iPod, iPad, iPhone media support ???
he ELM327 can be finagled into 33.3k mode for SWCAN communications by using the USER B protocol.
Here’s the list of commands from my notes that I use when typing directly to the ELM327 which has been attached to an 8055/8056 chip:
AT WS
AT L1
AT H1
AT PP 2C SV 40
AT PP 2C ON
AT PP 2D SV 0F
AT PP 2D ON
AT PP 2A OFF
AT WS
AT SP B
AT R0
AT CAF 0
AT L1
AT H1
ATMA (monitor the bus)
Some other notes that I use from time to time (my SWCAN bus supports 11 and 29-bit communications so this is used to observe/transmit it):
- To transmit in 29-bit mode
AT PP 2C SV 40
- To transmit in 11-bit mode, receive in 11-bit
AT PP 2C SV C0
- Transmit in 11-bit, receive 11 and 29 (seems to receive lots of false readings).
AT PP 2C SV A0
The following Modules are connected to the GM Lan Slow CAN Bus
1) Digital Radio Receiver (XM Radio - US Models)
2) Digital Video Disc (DVD) Control Module (Rear Seat DVD Player System)
3) Instrument Panel Cluster (IPC)
4) Driver Information Center (DIC)
5) HVAC Control Module (HCE)
6) Radio
7) Bluetooth Connector
8) Telematics Module (Onstar)
9) Theft Deterent Module (TDM)
10) Body Control Module (BCM)
11) Inflatable Restraint front passenger presence system (PPS) Module
12) Vehicle Communication Interface Module (VCIM)
13) Seat Interface Module
14) Remote Control Door Lock Receiver (RCDLR)
15) Object Alarm Module
16) Inflatable Restraint Sensing and Diagnostic Module
GM OBDII Connector Pinout
Pin 1 - SW-LS-CAN (33kB) or DW-FT-CAN (+) (<125kB)
Pin 2 - J1850
Pin 3 - MS-CAN (+) (95kB)
Pin 4 - Battery - (Chassis Ground)
Pin 5 - Signal Ground
Pin 6 - ISO 15765 HS-CAN (+) (500kB)
Pin 7 - K-Line
Pin 8 -
Pin 9 - DW-FT-CAN (-) (<125kB)
Pin 10 - PWM
Pin 11 - MS-CAN (-) (95kB)
Pin 12 - K-Line (KW82 Prot.)
Pin 13 - Reserved
Pin 14 - ISO 15765 HS-CAN (-) (500kB)
Pin 15 - L-Line
Pin 16 - Battery + (Constant 12V Power)