good find smitty, i was thinking about this last night, i have been checking on how the cpu communicates to the tool. the rj11 connector has 4 wires that are being unitized for communication, 2 of the wires go to 1 485 transceiver chip, and the other 2 wires go to another 485 transceiver chip. i was thinking the only thing that could be causing comm problems would be the 5 volt power supply to the chips, since you had changed out the cpu card. i have had 2 other people complain about this in the last 2 weeks, and you just happened to post this, thanks for the great post. I was wondering why the car would still run with no problems, but the communication would fail. seems that maybe the ripple is just enough to mess with the communication chips, and not with the other chips on the board. just thinking about why this would be, any thoughts