Headlight washers operating with screen wash.........

[Andyboy]

What's causing this? No, headlights aren't on and it's a very late 1991 car. I'm thinking it's the wash wipe relay............

[Brianmoooore]

Headlamp washers are controlled solely by one of the headlamp wiper motors; nothing to do with the control relay mounted on the washer bottle.
If the headlamp wipers are in the park position, then the washer motor should not be working. If they are stopped (seized) on the first part of their sequence, then the washer motor will run continuously.

[ian332isport]

Exactly as Brian said. For the record, it's the drivers side motor that controls the pump.

Ian.

[Andyboy]

.........replaced the control relay, full of nasty green corrosion inside. Problem solved. I can only imagine it was shorting out inside.

Cheers anyway Chaps.

[Brianmoooore]

If replacing the relay on the washer bottle had any effect on the headlamp washers, then someone has been changing the wiring!