OBD Signal breakout box

[Mute]

First post, hello! 

I want to make it easy to hook up my scope to the OBD adapter in my car, while a computer is connected. Cutting an OBD2 extension lead, soldering jacks inline for each wire and mounting it all in a wee project box is the easiest route.

I was wondering about introducing some protection for my instruments though. How would i best go about protecting against:

• Over voltage conditions - inline an opto coupler? Would this potentially screw with the RF signals?
• Polarity errors
• Over current - unlikely i'd have thought although i could be using more than 1 probe on the scope at a time so it's possible, maybe i should include fuses anyway

I'd like to make this a keeper, i can imagine using it many times over the years so a little extra effort up front to make a quality breakout box would be worthwhile.