Sender on thermostat housing

[drillmaster]

Hi everyone I'm quite new to the forum and have a 1990 caravelle 1.9 DG.
I've recently replaced the coolant pipes with stainless ones ( thanks for all the advice about that) and whilst I was at it took the thermostat and housing off and gave it a good clean etc and put back with new bolts.
My question is what is the red sender unit for on the thermostat housing… its not the one for the temperature gauge, and has a red/yellow and a brown wire into it.
It doesn't seem to make any difference whether it is connected or not nor which way round I put the wires onto it (the plug is missing and its just connected with the spade connectors).
Is this because its faulty or because it is redundant?
It at the facing forward part of the housing but I don't suppose it matters which sender goes into which hole anyway,,?
Any thoughts greatly appreciated!

Thanks in advance, Will

[itchyfeet]

My question is what is the red sender unit for on the thermostat housing… its not the one for the temperature gauge, and has a red/yellow and a brown wire into it.

those wire colours are temp guage sensor, it's not normally red.
https://www.brickwerks.co.uk/index.php/ ... k-wbx.html" onclick="window.open(this.href);return false;

the other position is the thermo switch for the carb heater circuit, those wires are blackand lilac/black and switch is blue.
https://www.brickwerks.co.uk/index.php/ ... -1807.html" onclick="window.open(this.href);return false;

so begs the question why does your temp guage work with the wires disconnected? or does it?

Best get a haynes for wiring diagrams. yes either sensor/switch in either position is ok

[drillmaster]

Mmmmm oops sorry I've got my post mixed up there The red/yellow are now connected to the black sender.I did have them connected to the red, but my temp gauge didn't work, as you have just pointed out. Does it matter which wire goes on which terminal, obviously which ever way it is now must be ok since its working…?
If I disconnect the red sensor then I presume I don't notice much difference unless it was a cold start then.

[marlinowner]

It doesn't matter which way around the connections are, it works either way.

[itchyfeet]

the connections can be either way as it's a temperature sensitive resistor and so not polorised.
Nothing wrong with spades as long as they have a covering rubber boot.

the other switch is normally blue and switches off hot, it's worth checking it works, it powers the relay in the black box, you can chevk with a multimeter that you have 12v on the manufold heater when cold but not when hot.

[drillmaster]

Brilliant! thanks both for that info. will test in the morning

[itchyfeet]

You're welcome.
worth putting your van details in your signature, year, engine body type etc, helps when you ask a question and forget to tell us. Worth joining the club too as it's free.

we like pictures of vans too

[drillmaster]

OK cool will get to it, thanks again