Rear washer won’t stop

[Gordir999]

Hi all, anybody had this problem before? The rear washer starts on its own and keeps running until it runs out of fluid no matter what you do with the switch. It did it a couple of years ago and I replaced the column stalk which stopped it happening but this week it’s done it again twice, the last time when I went over a bump on the road suggesting a loose connection somewhere? If there was a relay I would suspect the contacts failing but as far as I can see it’s switched directly from the BCM so could the column switch be broken again so soon?

[Lord Voltermore]

Does  sound like the switch  but  there could be a short circuit in the wires leading to the switch rather than the switch itself. .  Maybe vehicle movement is causing bare contacts or wires near each other to short circuit , completing the circuit.  .
That may have been the problem previously . Maybe when you disconnected terminals and  moved wires to replace the switch/column stalk  the source of the  short circuit was separated slightly. Until now. 

Rather than change the switch the first step may be to deliberately 'joggle ' the wires and connections near the switch   to  see if this either provokes the problem, or stops it..    This may help you diagnose exactly where the problem lies for a better fix. 
A squirt of switch/contact cleaner  may help as well.

[Brakballe]

You need a guy with a multimeter and a circuit diagram... me.. Unfortunately I'm located in Norway, have the multimeter but a bad cold I'm medicining with Jägermeister... 

But a circuit diagram and multimeter should sort what/where pretty quick. As previous suggested, a squirt with contact cleaner, I mean real contact cleaner not WD40'ish snake oil, here and there won't hurt either.

Meanwhile you should be able unplug it after removing the inner lining on the hatch?

And back to the medicine...

[Jocko]

Meanwhile you should be able unplug it after removing the inner lining on the hatch?

Problem is the washer, not the wiper.

[Brakballe]

Meanwhile you should be able unplug it after removing the inner lining on the hatch?

Problem is the washer, not the wiper.

Ah, yes, the pump sits in another place. My bad.

[Lord Voltermore]

On some cars there is only one washer pump for both front and rear.  For the rear  the switch may reverse polarity so the pump runs backwards. (water is then sent to the rear via  a one way valve)
I dont know if an unexpected polarity or method of earthing/grounding    might cause confusion  when circuit testing  or change the possibilities for a poor connection or short circuit.

[embee]

I don't know about the Jazz washers, but it is quite common in vehicle electrics to switch the ground/negative side of a device, not the positive feed side, as others have suggested above. This means that if there is a short  circuit to earth on the return side the device will run continuously, which sounds suspiciously like your washer problem so definitely something to look into.