Pull the CEM and clean the electrical connectors with MAF cleaner then reconnect.

If that does not work, one at a time disconnect the BCM, TCM, ECM.
See if doing so re establishes communication with the other two control modules. One of the three may be defective pulling down a common CAN bus line.

Even knowing with certainly it was the UEM I was not in a position to spend the amount of money required to replace the module. With the help of vegasjetskier’s post I took the rear mirror out and apart. I hooked it back up in the car with the electronics exposed and used a soldering iron to heat u...