Activating onboard CAN bus loses HDMI video on ubuntu 12.04 kernel 3.8 bone 20

Hello all;
I got bitten by BBB bee as well, it is a wonderful hardware, I am experimenting with its capabilities,
As I tried to activate on board CAN bus by following the following link
http://www.aero-box.co.uk/beaglebone-black#TOC-Enable-CANbus-device

I modified device tree and compiled it and then copied to /boot/dtbs folder, then reboot it
After reboot, I lost hdmi video which was fine before modification on Samsung LN32D403 at 1280x720@60Hz
then I ssh’ed to BBB to check out what is going on, I saw CAN bus activated but when I checked /sys/devices/bone_capemgr.*/slots
I dont see neither HDMI nor eMMC slots on the file, it seems on board 2GB memory and HDMI were not loaded…
Is this pinmux conflict (hdmi pins conflict with CAN pins?) that I am not aware off or kernel/device
tree modification error problem in the instructions of the web site I followed. But CAN bus was up and running

Another question, It shows a picture in the web site which demonstrate interfacing with the CAR OBD connector, I tried to contact the author of the website but there was no email, if he reads this post, can you post the schematic of the interfacing circuit? I know that BBB works with 3.3V level, do you have to use level converter to interface with the car OBDII

Any information or help greatly appreciated!
thanks
gezginbey