Hello!
I have strange problem with one unit that has been abused in a few different ways.
1. Cranked on booster while terminal on battery had poor connection to ground (sparks on terminal, etc.)
2. Bad ground on bad place
3. Connecting/disconnecting battery charger while running
4. ...
Repaired dead fets, and atmega, and everything was fine until abused again.
After fixing harness (all grouds good, placed where they should be), I can access it via rs232 while ignition is on, but no way to communicate while engine is running. Same with display, everything fine until I try to crank and run engine. When running, even USB2RS232 converter could not be recognized by windows (tried with two different converters and two laptops, also with third with real com port)
I changed max232, but no success, everything is same. What else could die?