mk triton windscreen washer wiring

[greybeard]

Got a fault with my mk triton 2.8t windscreen washer.
I'm chasing either a wiring diagram or info regarding windscreen washer electrical circuit. specifically if there is a relay in the circuit or not.

The washer motor runs and pumps water ok if I hard wire it to 12v.
With the washer motor disconnected(ie no load) I get power when I activate the washer/wiper stalk as expected. Although the voltage is slightly lower than I would expect. With no load I'd expect to see essentially battery voltage across the washer motor connector.
Measuring the voltage on the washer motor (ie under load) I'm only seeing ~0.5V. This is measured across the actual motor terminals.
This all suggests to me that there is a high resistance/dirty connection somewhere in the system that is causing a voltage drop under load that is preventing the washer motor from running.
Hence the info request to see if anyone knows if there is a relay in the circuit anywhere.
cheers
Rod