Jaguar S type windscreen washers inop?

iM a retired motor mechanic, with no knowledge on how to check for ecu supply faults.Electrics old style no problem,not these new units.My windscreen washers packed up in the last snow.Thinking it was a seized pump i renewed it,no joy,so checked the fuse again all ok.Then fitted new relay still no go.Last resort fitted new washer/wiper stalk.alas washers still no go.Main dealer not interested as car is 1999/2000 model,and say its probably the ecu.And these no longer available.. Any help on how to check for supply to the pump please.