The EVSE is checking that -12V shows up at the lower end of the PWM on the pilot pin. If the voltage rises then there is what you call a diode check error and you turn off the power relay, correct?
Where is this diode? How is its presence ensuring -12V? I just want to fully understand the whole diode check concept. thanks!
Diode is in the vehicle. It proves the resistance on the pilot line is intentional and not just a handle dropped in a puddle of mud.