Does anyone know if the outputs for yaw rate sensor, lateral acceleration sensor, steering wheel angle sensor, and ABS wheel speed sensors are available through OBD-II?

I'm putting together an automobile navigation system as the final project for my master's degree, and all of the above data would be useful, in addition to vehicle speed (which I know is available on the OBD II bus), external magnetic heading, GPS, and maybe accelerometers and gyros (if I can find good ones cheap:)).

Maybe autotap or a similar product has a list of all parameters? I haven't bought one yet, since I'd only need the hardware, and it'd be more educational to build a OBDII->RS232 converter myself. Or at least give it a try until I burn my eyebrows off, which is what usually happens when a software engineer starts to mess with hardware :)

Thanks

 

BTW, if they are available, what's the resolution of each one? Like is speed 100mph, or 100.3893mph. Is steering angle 24 degrees, or 24.5673 degrees, or what.

Thanks again.

PS: I know there is a difference between resolution and accuracy, but I doubt anyone except a GM engineer knows the accuracy of each sensor, so I'll settle for resolution for now.

 

Miles,
I work on Corvettes in the Chicagoland area, and I am pretty familar with the sensors that you are listing above. I am not quite sure what your asking. As you know OBD II is for components that will effect emission levels such as MAF, HO2S, CTS, MAP, etc. The steering wheel sensor, yaw rate sensor and the lateral accelerometer are used primarily for traction control. That is why you will only find these system codes in the TCS diagnostic portion in your drivers information center. The only system of the above mentioned that may be useful to you is the antilock brake system. With OBD II vehicles the ABS system is used to help the powertrain control module in determining a misfire. The parameters for OBD II are so strict today for example, that if you drove your vehicle over a set of rough railroad tracks your Malfunction Indicator Lamp (MIL) could illuminate because the vibration may be so great that it actually could throw off the ignition timing. The ABS system constantly montiors wheel speed and if the pcm detects a certain amount of wheel slip it may retard the timing to prevent the vehicle from misfiring and could also prevent excessive emissions. If I am anywhere in the ball park please let me know. thanks Jason
:) :chevy

 

There are several products available, such as autotap and "OBD-2", that connect to an OBD-II diagnostics port, and convert the data to a format that PC's serial ports can understand. They come with an application that let's you save the data to files, look at the current value, and plot the last few minutes of different paramaters. http://www.autotap.com/ http://www.obd-2.com/

I think emissions info is the bare minimum that OBD II is mandated to support, and that other data can be included by manufacturers, if they want to.

Yup. Using steering wheel angle, I was planning to calculate the turn rate of the vehicle. Lateral acceleration will also tell how fast the vehicle is turning, and yaw rate can be integrated numerically to give change in heading (direction of travel).

That's at least something. Using the different rotation speed of each wheel, it'll be possible to determine changes in heading.

Yeah, that's the kind of info I was looking for.

I just found a post on autotap's online forum, where someone else (also with a 99 corvette) asked the same questions I did. The person from autotap who answered seemed to indicate that a software upgrade is in progress for their product, to display ABS and active handling info: http://www.autotap.com/ubb/Forum3/HTML/000124.html

Thanks again.

 

GM connects it's OBDII port directly to the only control data buss of the car. There is a seperate E&C data buss connection on the port, but it is only to talk to the stereo and CD changer. If you were to short the the single wire, unbalanced DLC connection on the OBDII port to ground, you would kill all comunication between all the modules. If the single DLC "star" connection in the passenger footwell gets loose or corroded that same will happen.

When GM chose it's data interface to comply with OBDII, they screwed up big time. Every other manufacturer uses a different interface standard that is faster and has real noise immunity. Eventually GM will have to dump this interface standard and protocol because it is too slow and prone to noise.