Texx
Super Moderator
I've just checked a 2 plug GT ECU I have here and there are definitely +B and +B1 terminals in the 16P connector, both terminals have continuity inside the ECU so +12v would only need to be applied to one of the two terminals to keep the ECU alive. However, like I said before there is no +B1 terminal shown on the wiring diagram for the EP91 4E-FTE and as you say there is no pin 1 in the 12P connector, so I'm a little bemused as to why the engine did not stall when you cut the +12v at pin 7 of the 12P connector. If you definitely did cut the correct wire to pin 7 then there must be another +12v feed into the 3 plug ECU that is keeping it alive.
Have a check for continuity between pin 7 of the ECU terminals and the other 11 pins, do this at the ECU with the connector removed. If you get continuity between pin 7 and another pin other than pin 1 you'll need to identify what that pin is and what is feeding it.
Have a check for continuity between pin 7 of the ECU terminals and the other 11 pins, do this at the ECU with the connector removed. If you get continuity between pin 7 and another pin other than pin 1 you'll need to identify what that pin is and what is feeding it.