Hi IanThe interesting thing is that the diagram shows wire 7842 is spliced (E784). Your wiring data may show where that spice is. I am not sure how the spice is implemented but it could be an inline plug and socket so it would be worth looking for and checking.
I think i have make a mistake as the wiring diagram was for a Car with ESP which mine doesn't have.
The splice in the wire would (E784) would be where is would have tire inflation detection that how I realized I had clicked on the wrong one at the start so i have reselected the car without ESP and below is the diagram which this one doesn't have the splice in the wire. It does have a double number thou 7842A/7842E not sure what this means.