It's a very different issue if ALL electronics give a failure warning vs. just one unit, both leading to limp mode, see the case of the OP. Limp mode is caused by the electronics failing due to a low voltage present.

A very sneaky flaw (once you have new battery fully charged and such obvious checked) is a weak alternator. It fails gradually, then occasionally not giving the full voltage, thus car voltage going low while driving. We all know low means it's just a tad under the needed level for the computers. Car will still start just fine.

How to check? Make sure you are ALWAYS getting 14V or more, even at idle. Easy to measure at the battery, and you have to do this often to catch the alternator while its failing. It's the alternator brushes that can wear out this way. No dash warning light, no relevant codes easy to spot from the mess of all those "failing" equipment. Often the gremlins go away by restarting the car.
Back in the garage, you might not find any issues. A new alternator is not expensive, but its lots of work to change, do other front end preventive work at the same effort.
Bosch alternators fail after 200k up to 250k km (after 125k miles).

 

Thank you, Gary; FYI: I keep a solar charger on the battery all the time and the battery is fairly new. But I haven't tested the alternator except that I think I got a 14V+ reading while at idle last time I checked. This circuit from ABS module to TCM to ECM seems to be erratic and a problem because the last shop I went to just said "the ABS wasn't communicating ...". Well, YEAH....I ALL READY KNEW THAT....HERE'S YOUR $175. I know I need to do a continuity test for that circuit, but just haven't had the time. Maybe I should start with a hard discharge to stop the current "limp" mode (acts like its in 5th gear from start). I have never had the wheel ABS sensors checked.