Reviving this thread - 3 yrs old but I know rcr1978 is still around
I've been fighting similar issues with the CTS2 and my LB7. Just like yours, the DSP5 switching always works fine, but occasionally all the PIDs freeze, except for the two analog EAS probes I'm using with the unit - EGT (right side ex. manifold) and boost PSI (in the wastegate tube). Only seems to happen maybe once in every 10-20 drive cycles. When it happens, the truck continues to run fine, but the A/C quits and the security light turns on in the cluster. Very rare, but I have seen my fuel gauge go to empty a couple of times. If you try and read DTCs, sometimes there are none, sometimes there's a bunch of Uxxxx codes indicating the class 2 data bus is hosed. Attempting to return the unit to the main monitor screen always results in a "Unit cannot communicate with vehicle - powering down". Normally a key off/on cycle clears everything, but sometimes I need to clear the Uxxx DTCs first, depending on which ones get set.
I did all the usual updating the CTS2, got a new OBD2 connection cord from Edge, even swapped to a completely new (probably refurb) unit they sent me, but the problem persists. I even bought a new ECM, programmed it with my DSP5 tunes and problem persists with this 2nd ECM. After a bunch of research, another guy on a different forum was chasing the same problem, someone suggested replacing the ignition switch on the column. I replaced mine as well, didn't fix. The only other variable I can think of regarding the class 2 data bus is that I have an aftermarket stereo with a PAC RP5-GM11 module to regain the chime and steering wheel control functionality that the stock stereo had. Everything else is stock electronics.
Were you able to find any solution?
The CTS2 is about ready to hit the trash. Done with the flaky behavior and I'm probably going back to a good old reliable DSP5 switch with analog gauges, especially given what I've been hearing about the CTS3 being full of bugs as well. Banks iDash seems to be plug & play in the OBD2 port for 2008+ vehicles only. Seems they offer the 66563 standalone 12v only iDash gauge, with the 4 analog sensor input adapter plus the pressure + EGT sensor I would be back to the basics this way as well.