[edit2] i just used a power supply to put 5V on pin 1 of CN201 and 12V on pin 6 and did not get any current flow thru the Zener diodes, so i'm thinking the "30" means 30. and not 3.0 volts. So now i'm back to thinking the discrete SDW is nominal 12V battery system voltage levels.
[edit1] i never determined the Zener voltage of ZD 202 and 203, both are marked "30", but if that means 3.0 and not 30., then what i wrote here is not correct. Maybe the DCSW and SDW are 5 or 3.3V signal levels?
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Yes you are right it is battery voltage, i.e. what i was calling the +12V Switched system voltage that comes in on the yellow wire to pin 8 of E03 connector to the OBC, and gets routed down to CN201 connector on the DCDC board pin 6.
This system voltage gets returned on pin 7 "SDW" of CN201 up to the Brown wire of pin 11 in E03 connector to the EV-ECU. This happens when the transistor Q210 is turned ON to complete the path; the drive for Q210 occurs when all the check circuits in the DCDC are "happy".
Not sure what line you are calling a 5V DCDC enable? Is the DCSW a 5V output from the EV-ECU?
This is nearly drawn out in the diagram, just draw a line from the end of pin 8 over to the top of the transistor shown on pin11 of E03.