Out of curiosity I just took a quick peep at the GDI electrics. So it looks like the GDI's CAN high/low signal wires enter through the 'Chassis to Engine' connector directly from the ECU (pins 13 and 14). The wires then appear to be distributed using 5 wire twisted pair splices, SP7 and SP8 (most probably located on short stubs behind the connector) with one pair of wires then running directly off to the 'VDO Master Gauge' connector.

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Those splices may be weak points? I hope they have been done with more care than the regular barrel splices on the loom.
Here's a pic of an earth splice with the insulation off that fell apart and needed repair on Monty.
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Roger
2011 Plus 4