Have you made any changes to system via AlphaOBD or upgrades like new mirrors or taillights? Assume they were working correctly at first, did anything happen just before they went out or did you do anything like heavily washing the underbody or elsewhere with a high powered pressure washer? Did they check all fuses, make sure they are seated properly? Has wiring been checked for proper connection? Those are areas I would start at. Since they should have already run for codes my cheap next act would be to disconnect the battery, let it discharge and clear everything, and reconnect and run a couple of cycles (start, drive 20 or so minutes, shut down, repeat 2-3 times) especially if heavy water was encountered. If nothing out of ordinary in use and they can't diagnose then they may need to start throwing parts at it. Could be a bad sensor or module. Try connecting with
@RamCares as well.
Good luck.
Here is a video to provide some help on how it works.
https://youtu.be/_9KIn9uZqXE?si=tiNC2wC8BhBt86I5