I’ve seen just the serial port fail on a 188e before. If you can talk to another car with the same setup & network and you never see direct connection on this one it’s probably the board. Tac20s can take a long time to connect but when that happens you’ll see it bounce back and forth between direct connection and no device connected. If you’re really lucky there could be an adjusted job file on a USB stick or floppy but most likely you’ll have to get a factory job file and LON config and adjust the thing from scratch.
