Coolant alarm not working

[Sharbee22]

Hi, I have a coolant alarm fitted in my Bongo. The alarm was in it when I got the Bongo about a year ago.
I take it if the alarm is not working then it's just plain broken?
It has 12V/0V going to it and it's connected to a screw in the coolant tank. It shows no signs of life...

[gilly99]

Eh? It's a low coolant alarm; it only lights up & sounds for a few seconds (test) when key is first turned in the ignition and then again (of course) when the coolant drops below that screw in the header tank. They are bulletproof - likely just a bad earth or broken wire.

[g8dhe]

As above its a LOW coolant alarm, it sounds when you have a coolant leak and the level in the tank drops below the level of the screw.
When you first turn on the ignition it will also self-test by sounding the alarm for a few seconds, then it will go quiet until either you loose all your coolant or the next switch on of the ignition.

[Sharbee22]

Eh? It's a low coolant alarm; it only lights up & sounds for a few seconds (test) when key is first turned in the ignition and then again (of course) when the coolant drops below that screw in the header tank. They are bulletproof - likely just a bad earth or broken wire.

Hello.
Mine does nothing (as in it doesn't make a noise when the key is turned or when the connection to the screw is opened).
My volt meter tells me that the supply to the alarm is not bad. It goes on and off with the ignition.
This leads to me conclude that the unit is faulty and not repairable if they are supposed to be bulletproof.
Thank you anyway.

[gilly99]

Like I say, would suspect a broken wire. Can't you disconnect the ground to the tank at the unit, and then test the unit by grounding the pin direct to earth? That would simulate a good connection through the coolant, so it should go through it's little test when turning the ignition.

[g8dhe]

Have you actually checked that you have the -ve/Ground connection at the module ? Lots of people when checking the +ve supply simply clip the -ve probe of the meter onto a metal surface easily reached rather than actually testing between the -ve and +ve supply wires to the module itself.

[Sharbee22]

I'm doubting myself and rightly so.
Thank you both.
I may well have used the nearest bit of chassis to check the 12V.
When I'm next able to, I will check the 0V connection (although it did feel solid enough, I recall) and furthermore do as Gilly said.
Have a lovely evening, all.

[Bob]

If it’s one of Haydn's all the info above is correct, but there are some 'less good' ones out there which have their quirks, including no self test.

[Sharbee22]

I finally got around to checking the connection to the Haydn coolant alarm.
It has switched power right to the unit but does nothing. Makes no sound when power is switched to it.
So, it must be broken

(It is supposed to show signs of life when power is applied, yes? Coolant or not?)