The rear screen washer on my wife's 2014 Fiesta has stopped working although the front continues to work. This means the pump is working and there is fluid in the tank but when the rear washer is switched on there is nothing, not even the sound of the pump. We took it to our local garage who said that it is some unit which controls it which needs changing but they will not touch electrics.

Any ideas where the unit is, how easy it is to replace and where I might get a replacement without a mortgage for a main dealer one?

The screen wash pump (and a great many other things) is controlled by the Body Control Module (BCM) which is part of the passenger compartment fusebox.

When you operate the stalk on the steering column for the screen wash the signal is sent to the BCM, it then works out if you want the front or rear screen and depending on which it is, the pump is rotated clockwise or anti-clockwise.

If the pump works for the front and not for the back the problem is either a faulty stalk switch or a problem with the BCM. For the purposes of testing you can use a multimeter and check that when the stalk is operated that a 12V signal is being sent to the BCM.

It is common on some models for the pins inside the connector of the BCM to become corroded due to water ingress. Disconnect the negative battery terminal before investigating the BCM connectors. If you don't feel confident to do this then any good Auto Electrician will be able to do it.

If the BCM requires replacing this is quite costly and will require programming for your car

8 minutes ago, unofix said:

When you operate the stalk on the steering column for the screen wash the signal is sent to the BCM, it then works out if you want the front or rear screen and depending on which it is, the pump is rotated clockwise or anti-clockwise...

 

Great description of this deceptively simple operation - said it before, but every day's a school day!