Ultrasonic sensor interface

Hi, I am making some progress on my project and would just like someone to check out my circuit. The sensor in this schematic is powered by 12v, but the comm line runs on 10.1v hence the voltage divider running to Q1. When I bit bang the digital listen command to the sensor, it pulls the comm line low when it hears an echo. The trouble is, it doesn’t pull it completely low, only down to about 3v. I was thinking If I put D1 inline, it would solve my problem, anything below 5v won’t make it past the diode, so at the d22 pin 3v will be seen as 0 right? Is this an appropriate solution to this problem? or is there a more elegant way to solve it?

senseschem1.fzz (10 KB)

Can you post an image (instead of fzz)?

Also, a brief description of what you're doing? It sounds like a continuation of a previous thread - you should give a brief summary of that to orient us.