I tried the screen dim with the iPad3, iPhone4, and iPod4. None of them will timeout. Can you guys try cycling the power off and rebooting your device and see if that fixes the timeout. Next step I would suggest is completely remove DashCommand and re install. You will lose all of your vehicle settings and log files if you delete DashCommand, so be warned. I am starting to wonder if some files stay cached in the iOS system on an update?
Tried the power cycle as soon as I experienced the issue. Did not fix the issue. For me, I connect my BT1 to the OBDII port and connect to it with my phone and start DashCommand. I always get the dim/lock after this. I kill the task and restart DashCommand from scratch and works 100% stable. If I minimize DashCommand while connected (to check mail or something) and then reopen DashCommand, I am taken directly to the tab I was once monitoring but get the "red" connection. After 30 seconds (per settings), DashCommand re-establishes the link, it turns green and logging starts. I'll get the dim/lock issue 100% of the time doing this.
Not willing to completely delete and re-enter all my data back into DashCommand to help troubleshoot, sorry. Perhaps someone else can try and confirm if this fixes it.