Yesterday I went for my first drive after replacing the hose on my Cruise Control. It still doesnt work.... I have also put a battery on the motor as a test, the Diaphragm pulls in, no problem...Before I dig out rave and start going through the diagnostic waterfall, what is the next most obvious probem to check?

If the diaphragm pulls in, then you must have also activated the little vacuum relay valve inside. Sounds like the small 4mm tubing is ok as well or the diaphragm would not pull in. Best to go through the trouble-shooting guide, as that verifies the steering buttons, the red relay & the ECU.

My green P38 has been intermittent for a while. I originally thought it was the ecu based on the trouble shooting, BUT, after trying that one & a spare in the other P38, I decided to install the later AMR5700 ECU so I could get diagnostics. Problem still exists with intermittent engage. I now suspect the little vacuum relay doesn't seal properly, so gonna find another on eBay.