Not had the enthusiasm to sort out current draw on the wipers, but did have a quick play to establish which wire does what which is not so obvious for all of them.
Simplest is the grey wire which is the fast speed, seems to work without help from any of the others.
Blue during intermittent, when relay clicks on, starts wipers, when relay clicks off, stops wipers. During slow seems to run them all the time.
Blue/White moves off start position in slow mode, not really sure what else it is used for as appears a little redundant?
Blue/Black This is permanent power which is used to return wipers when you switch off etc.
Hope this is useful to someone!
Peter