[fordem]

The first challenge here is determining what a grand Vitara sport 55 plate is - you're posting in the second gen (1999~2005) section, but, there was, as far as I know, never a second gen Grand Vitara Sport, so I'm thinking you might have a third gen. Why does it matter, third gens control the wipers using a BCM (Body Control Module), second gens don't.

The symptoms suggest a defective ground.

 

[fordem]

The vehicle at the top is a second gen, lower down are third & fourth.

 

[fordem]

No, it should still hold true - late 2005 second gens should have the washer pumps in the left front fender, along with the indicator ground, and if the ground is poor you can get a backfeed through the pumps into the wipers and all sorts of crazy symptoms.

 

[fordem]

As far as you can see is not good enough, remove them wire brush them & refit - there's a 99% probability that your symptoms are caused by one or more bad grounds somewhere on the vehicle.