Big Bob

Sorry I've taken so long to reply, finding the fault was more luck then anything else. I just noticed the broken wire inside the conduit at the join where the wires from the actuators meet the main harness low down in front of the g/box. The conduit on mine is open at the joins which is an obvious weak point. I had been trying to find a decent (understandable) wiring diagram without success. But I have some experience of data links from HGV work & they are a source of problems. Data links are fairly obvious as they are always twisted pairs of wires to reduce interference. Be careful when testing as they run on variable low voltage signals, if you put full voltage down them it can damage ECU's. I would recommend stripping off the conduit & inspect visually, you could also pull the wires to see if they spring which means the wire is broken inside the insulation.
Sorry again that I can't be more helpful than this.
Hope you find your fault.