Mondeo Mk4 wipers keep running

[Tant]

All

Driving home tonight in my 2010 2.0 tdci zetec and had a strange fault with the front wipers.

With them running on intermittent, they started by doing the odd "stutter", stopping mid wipe for a fraction of a second.

After that, they started running continuously, and would not switch off slow speed, unless I moved the stalk to fast speed whereupon they would speed up.

At one point I pulled in, switched the engine off, removed the keys, and they still kept running on slow speed. When I got home, I disconnected the battery for 30 seconds, reconnected it and all seems OK again.

However, I'm worried it will do it again. Tonight was no problem as it was raining, but if it was dry I fear this could burn out the motor if run on a dry screen.

The few posts on Talk Ford do not say much about a solution, so I'm looking for a fix...sticky relay possibly? What I don't get is why they do it with the ignition off. Is the circuit live at all times so they park if you pull the keys out before they are parked?

Any help appreciated
Ant