Screenwash sWitch
 

I finally got around to changing the screenwash pump yesterday, on the ZT-T I bought from BigAde. New pump is visually very similar to old, with one electrical and 2 hose connections, and I now have 4 fine jets onto the front screen. The problem now is that I still get these just 4 fine jets when operating the rear washer switch, and nothing to the rear!


As there are only 2 wires to the pump, how does it know which way to send the water? Or, if it always sends to both front and rear, why are there 2 separate switches?

Hi Peter,

The ZT-T washer wiring diagram is confusing to say the least. The sub-loom from the rear wash/wipe controls isn't shown at all!

I'd like to see this if you fancy a day trip to London. :) But first, is there absolutely definitely only one pump in the reservoir (my SD1 had two, one above the other)?

Simon

I haven't looked for the diagram as yet, not sure it would help. I did idly wonder if the pump would spin either way depending if voltage was reversed, but the pipes are in a definite tee off the pump. I believe models with headlamp washers have a second pump, and the wiring is there for that. I can't even see that back-pressure from a blocked rear nozzle would cause the fluid to go to the front. I hope someone knows how this set-up works or can tell me the pump (supplied by the PO) is wrong.


As for day trips to London, I have a short walk to the big metal cars than run in queues thanks, but it's lovely down here on the South Coast!

The Haynes wiring diagram is pretty useless, as it only shows one switch.

This is my pump, which has just two wires going to it and two pipes coming from it...

https://www.the75andztclub.co.uk/for...3a1bccf89a.jpg

I would imagine that for the rear washer, the polarity is reversed and the motor runs in the opposite direction. If yours doesn't, it looks like it's either faulty, or the wrong pump.

Can you check with a meter to see if the polarity is reversed?

What's your thinking Dave? If the motor ran backwards, wouldn't it pump water from the tubes back into the reservoir? :shrug:

What are the other two wires in your photo?

Simon

I'm thinking that there's a valve to direct the fluid, depending on which way it's running.

The other two wires are for the level sensor.

Yes the pump reverses direction for the rear washer, the valve controls which outlet is supplied ;)

Russ

Peter, could you report back on Dave's suggestion please?

Simon

Thank you.




It's the next job on my list now, when I can get out there. I guess I need to figure out whether the fault lies with the supply, motor or valve.

How does this system work then Russ?

Simon