Last night I dived into the garage again to get to the bottom of this ECU issue. This is the ECU plug and as you can see there are some intentional blank sockets, but some of the pins are also further recessed than they should be. Once the black cover is removed the pink section can slide to one side and half release the pins. With an insertion/removal tool you can then fully remove the pin if required. When I originally installed the connector, the pins 53, 52, 51 and been soldered to a replacement loom cable so I replaced and re-soldered them. These pins didn’t look perfect to be honest so I have pushed them forward and ensured they are seated in the pink locking ring, then rebuild the plug.
The ECU had also been located in the rear of the chassis/body alcove but this is difficult to get to and I’ve decided to relocate it. Although the relocation is not perfect and I hate afterthoughts I think it will be useful until I can be sure the wiring is okay.
You can see the ECU to the left of this photo, in the rear of the engine bay on an aluminium extrusion. I need to re=wrap the end of the loom where it enters the ECU plug but again, until I’m sure everything is okay I’ll leave it as is.
and a few other photos…