I was being conservative for any over voltages from the vehicle, hence the Zener. I just found another circuit with the same #2 VD setup as above. 2.2k to ground and 33k to the output yields 1.7 volts when 13.8 volts is applied. No cap and no Zener and on a 16F628A, RB0.

This is all new to me as I've been using opto's. Never looked at the datasheet that way as I had never intended to connect it directly. Didn't think you could, but now I'm finding out that you can. Looking to explore it further. Right now, my pins are RB0, RB1 and RB2.