ODB-II extended diagnostics, on a Ford?

valen

I'm playing around with a microcontroller, trying to make it talk to the ODB-II port of my Ford SMAX. I was hoping to get data on oxygen levels in the engine in various scenarios, maybe the long term or short term trim.

After spending a while hacking away on it, it's far less informative than I'd like.

A run through of the code does show a bunch of interesting data. but all the standard ODB-II commands around sensors are returning "NO DATA", which makes me sad.

Anyone know how this works ? Do you have to enable some proprietary mode to get the real data out of this ? Or are Ford just shi*e ? Do other vehicles give more data ?

The code is above, if you are interested in hacking on the ODB-II port, let me know and I can share what I've learned over the last while.

scannerd

the ODB-II data should not be proprietary but there are 5 or so different standards that might effect your code?, I have a advanced scanner which runs through each protocol until it finds the one the car speaks.

valen

Are any of these 'standards' documented anywhere ?

scannerd

SAE J1850 PWM

This signal is Pulse Width Modulation, which runs at 41.6 kbps. This protocol is generally used on Ford vehicles.

SAE J1850 PWM
Feature Description
BUS + Pin 2
BUS - Pin 10
12V Pin 16
GND Pins 4, 5
Bus State: Active when BUS + is pulled HIGH, BUS - is pulled LOW
Maximum Signal Voltage: 5V
Minimum Signal Voltage: 0V
Number of bytes: 12
Bit Timing: '1' bit - 8uS, '0' bit - 16uS, Start of Frame - 48uS

scannerd

also read this

https://learn.sparkfun.com/tutorials/getting-started-with-obd-ii

valen

Yeah, I've gotten a lot further than the Sparkfun tutorial - I've polled every ODB PID in the standard, and most of them return 'No Data', which is my confusion. Check out the links in my original post.