Oupss !! You are right, here is the good wiring : I don't measured exactly, but it's very fast : When connecting to the car, the EVSE is in state A, and the car ask for state B. The EVSE sends the 5% PWM, and very quickly the car switches to state C, to tell the EVSE to switch to CAN digital communication. At this step your EVSE must set the CP line to -12V continuous. You have approx 1s to detect the car switched to state C and set -12V on CP line before it sends the first CAN frame. Yes, that's this schematic : Surrounded parts are components I added for the CAN interface. In my case the microcontroller of my EVSE box doesn't support CAN, thus I used another board, but that's the same schematic, CAN_TX and CAN_RX just go on another board in my case (with common GND of course). You are right that's a good idea !