hi all, need help. The big round wiring loom connector that sits between the rocker cover and the firewall with multiple wires. The black wire on the firewall side of the join was connected to the red wire on my TPS. This didn't match up with the Gregory's wiring diagram. I have changed where the TPS red gets power from according to the wiring diagram, but have no idea what this black wire is for except maybe an earth by its colour? Can anyone please advise? Thanks