I have a problem with my rear wiper: it works fine but the water squirt no longer does. I've had the pump tested and it's fine and as the wiper works, I'm guessing the link between the switch and the pump is OK so that just leaves the switch itself.

My question is how do I get to the switch to test it and how do I test it (I have a multimeter)? I believe the switch is a combination unit with the hazard and central locking switch on it. I don't want to buy a new unit (over £50!) to find the problem is somewhere else.

TIA