Im working on a standalone OBDII scanner and display for my car using an Arduino Uno. The car is a 1999 Pontiac Trans Am which uses the VPW protocol so ill be using an OBD VPW to RS232 interpreter chip. I think ill be powering the Arduino off the 8v off the 78L08 voltage regulator and tie arduino ground to chassis ground.
My questions are:
Are there any major software problems I may run in to?
Do I have enough power and signal isolation to protect the arduino (and my cars ECU)? (Do I need an opto-isolator or something?)
Any other foreseeable problems?