cmaciel

Hello,
Is there public documentation (i.e. online or in print available for purchase) about how to communicate with the several microcontrollers in the Corvette? Not only OBD2 information, but also how to read speed and g-force information from the computer, and also the microcontroller interface to the NPP (I know there are tons of solutions out there to control it, but I would like to see the spec, and also play with it, do it myself). From what I know, the systems should be connected using a CANbus interface, but are there published specs?
Thanks
Cesar

Donkey

I believe you can get access to this type of information through a SEMA membership.

cmaciel

Do you have more details on this? After I become a member, where do I go for this type of information (sorry for asking, but I have no idea on how it works).
Thanks
Cesar

danl72

Would be interested to know.

GermanCars

Your talking about the digital CAN bus language? Although there are only so many ways skin a cat so to speak, what your asking is usually proprietary and is guarded pretty closely by the manufacturers. If you are a well known aftermarket manufacturer you MIGHT get some cooperation. Otherwise you will likely have to backward engineer it or pay someone to.

tpereira

this would be nice info to have, wonder why its not public info

GermanCars

Probably because they spend millions of dollars developing the language and the system it supports. Not exactly shareware

torquetube

Information-hiding paranoia is standard operating procedure these days throughout the engineering fields. Remember when service manuals for instruments and appliances used to include complete schematics? Those days are sadly over.

Usually none of the stuff kept secret would be of material benefit to the competition, but they do it anyway.

If the O.P. finds anything out, I urge you to share it with the rest of us!

GermanCars

Someone is doing it.

http://forums.corvetteforum.com/show....php?t=2037111

Pipedreams

So I will share with you what I found out. You will not find detailed published information on the CAN Bus interface. This information is only released to certified companies that have contracts / agreements to develop electronics to interoperate with CAN Bus. I have spoken to a number of companies that work with GM now on CAN Bus electronics. They said even if the money was not an issue $10k + it’s unlikely you would get GM to approve it. You have to understand that messing with the CAN Bus can cause all types of problems in the cars nerve system. Everything from antilock brakes to airbag deployment are controlled by this interface. Even worse I was told that GM will encode these interface in the next year, so anything you may develop now will be throw away.

TLK

Probably you need to look on the web for more general "hacking the CAN bus" type stuff. I've seen it when I was working on my M3 carputer (IBUS) interface. CAN bus and GM cars have some stuff out on the web, like the commands for windows etc. Try carputer websites (MP3car.com) As Corvettes are smaller in number than other GM cars, there may not be as much enthusiast hacking going on. Still, using what you find for other GM cars and then experimenting to try to snoop or just try commands trial and error may get you someplace.

The Window Valet is an example of a 3rd party product that uses the CAN bus, and even interfaces the software through the OBD-II connector. They may have paid the big bucks for the official information.

keyplyr

You can read it on your iPhone or GooglePhone by installing a $10 program called Dynolicious: http://dynolicious.com/

Some of the performance metrics Dynolicious can measure:

• 0-60 Acceleration
• 1/4 Mile Elapsed Time
• Lateral G's
• Horsepower

Other tests:

• Other Speed Tests (0-10 MPH through 0-100 MPH in 10MPH increments)
• Quarter Mile Elapsed Time
• Quarter Mile Trap Speed
• Elapsed Time and Trap Speed for standard intervals (60', 330', 1/8 Mi, 1000')
• Lateral G's (current and peak)
• Braking G's (current and peak)
• Wheel Horsepower
• Estimated Engine Horsepower

leres

There are two buses in a C6 Corvette: CAN and class 2. The BCM is on both buses and acts as a gateway between them.

Class 2:

• Heads Up Display (HUD) [optional: UV6]
• Instrument Panel Cluster (IPC)
• Driver Door Module (DDM)
• Driver Door Switch (DDS)
• Driver Position Module (DPM)
• Inflatable Restraint Sensing and Diagnostic Module (SDM)
• Digital Radio Receiver (DRR) [optional: U2K - XM satellite radio]
• HVAC Control Module
• Radio
• Remote Control Door Lock Receiver (RCDLR)
• Body Control Module (BCM)
• Front Passenger Door Module (PDM)
• Vehicle Communication Interface Module (VCIM) [optional: UE1 - OnStar]
• Exhaust Tail Pipe Flow Valve Control Module [optional: LS7]
• Steering Column Lock Control Module (SCLCM) [optional: MYC - paddle shifter transmission]
• Folding Top Controller (FTC) [optional: CM7 - convertible]

High speed GMLAN (CAN bus):

• Electronic Brake Control Module (EBCM)
• Engine Control Module (ECM)
• Body Control Module (BCM)
• Vehicle Communication Interface Module (VCIM) [optional: UE1 - OnStar]
• Electronic Suspension Control Module (ESC) [optional: F55 - suspension]
• Transmission Control Module (TCM) [optional: MYC - automatic transmission]

GermanCars

That's a really neat tool but it isn't reading vehicle data. It uses a G meter and GPS that is built into the phone for the calculations

cmaciel

Leres, do you have docs on this? Did you purchase them? If so, where and how much? If not, would you mind sharing the information. Seems (from this thread and from the HUD thread) that you've done some work with the communication buses, so I'd like to get info if you wanna share it.
Thanks
Cesar

leres

For about $60 a pop, you can buy parts of the spec from sae.org. J1850 covers the electrical protocol and and J2178-1 through J2178-4 cover non-emissions messages. However only generic codes are documented. For example, things like door locks and engine rpm are covered but things like HUD and XM radio commands are not. The latter are manufacturer specific and are not covered by the standards (except that ranges of codes for use by manufacturers is reserved).

You don't have to build hardware to talk to the J1850/class-2 bus. I like the ELM 327 chip. It's found in serial/usb scan tools such as the ElmScan 5 product line.

keyplyr

I understand that, and thanks for posting the clarification. Sorry, I didn't intend to imply it was "tapped into" the ECM and that the data was 100% accurate or specific to the car itself.

However, IMO for approximately $10 (if your phone supports this software) it is a useful and interesting toy and since the new Google phone platform (Android) is open for software developers, there should be other clever utilities coming our way in the future

ben dover

Let's hope so.