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Low coolant alarm install

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After having the low coolant alarm sat here waiting for a spare hr or so to fit it.

well today I did

I installed the float level switch and wired in the control box

I used the spare Gearbox temp warning lamp on the dash to indicate a problem

what isn't visible is the Buzzer that I added to the circuit, there is no way unless you are deaf that you could ignore the noise, I fitted the buzzer behind the dash and it is still very loud.

Buzzer came from Ebay for about £3 delivered.

ORIGINAL THREAD

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I fitted a similar unit recently but used a interface from Tim of TEB Technology [PM me for address] & the RR float switch header tank cap coolant level sensor PRC7925,

copied from my posts here

Fri Sep 18, 2009

fitted the interface today, all working & I've used the water in fuel warning light of my Td5 warning light pack to tell me when the level is low, the green led on the interface is ON when coolant level is OK, so I've a light for both good & bad notifications. I'll sort my wiring diagram out over the weekend & add it to this thread.

Sat Sep 19, 2009

edited to add my wiring diagram as promised, I've also added a 3mm green led [Maplin CK35] a 680R resistor [Maplin M680R] & a Press to Test switch [Maplin FH59] to the white wire of the interface & located these in the upper left corner of the instrument pack [refer to small diagram on wiring diagram] the interface led is visible at the lower right between the fuel gauge & warning light panel of my Td5 instrument pack.

so with the ignition on the interface green led [number 1] is lit [= correct coolant level] the PTT switch is pressed & it's green led lights [number 2 & 4]as a good test, with a low coolant level or one of the cap wires disconnected the interface green led is out & the amber [3] [water in fuel light] now my low coolant level light is on & the PTT switch/led is non functional [doesn't light]

Sun Sep 20, 2009

Once I decided on the location for the interface unit, it was fairly easy to connect into my 110 which isn't a Td5, it just has a Td5 instrument pack which I fitted a few months ago, the water in fuel light [if used on a non Td5 vehicle] needs a positive power spply to switch it on [illuminate] so when the float/coolant level is low it comes on, thereby giving a correct & low coolant warning, I haven't fitted a alarm to it, I've used araldite to hold the interface in it's new home & the led needs a 5mm hole to show/fit in.

Wed Sep 23, 2009

this interface seems to be working fine, I had to adjust the ign controlled 12v feed wire yesterday, so now it comes off a ign controlled green wire that feeds the fuel & water temp gauges via a 5amp fuse to the 12v feed in to the interface, that's stopped the green led flickering & all is now 10/10.

wiring diagram as fitted to my 110.

File0472.jpg

the parts diagram details the float switch cap I fitted

 

coolantsensorcap.jpg

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Yes I fitted one from Tim as well. Actually the second one he made. As I have an alli header tank I used the Range Rover float switch.

I also modified mine to give a coolant level check with a push switch. I should still have the diagram for that bit.

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A bit of a thread revival here... but I had a cunning idea the other day...

I purchased a spanking new break fluid resovoir cap low level sensor from fleebay for a small sum and I'm planning on doing a wee modification to then pop it in the water header tank, fingers crossed it might actually work...

Mav

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depending on which header tank you have, the early brass oval version or the deeper black or translucent version, for the later deeper tank the brake fluid level float won't be long enough. but might be fine for the older tank, how are you going to fit it to the tank, as it needs to be spot on vertical to work correctly.

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depending on which header tank you have, the early brass oval version or the deeper black or translucent version, for the later deeper tank the brake fluid level float won't be long enough. but might be fine for the older tank, how are you going to fit it to the tank, as it needs to be spot on vertical to work correctly.

Standby, all will be revealed :D

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I have one of these original kits, never fitted, supplied by Tony.(white 90)

For sale if anyone is interested, Price is £60, what I paid, PM me please.

John

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John,

PM'd a couple of days ago... Have you still got the kit?

Donald

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I know that there are many threads on this topic, and they all seem to lose me in electronickery. As a committed non-electrical guy, and as asked on one of the other forum threads referenced in this thread, which didn't receive a response, why can't the low level switch in the header tank cap directly activate an alarm buzzer or light?

Mike

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Because it works the wrong way around. It lets through current when the level is OK.

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I'm still not sure that I understand. If "it lets through current when the level is OK", why not have the low level switch feeding the coil of a Normally Closed relay? At normal coolant level, being energized, the contacts would be open, so no alarm. Then, when a low level occurs the power supply will be lost and the relay will close, thereby sounding the alarm. Or am I totally misunderstanding the system and the way relays work?

Mike

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That would work just fine in theory.

I'm not sure of the specs, but it might be that the coolant sensor isn't rated for the current necessary to hold a relay open.

You could always fit one of these instead: http://www.ebay.co.uk/itm/Water-Level-Sensor-Horizontal-Liquid-PP-Side-Mount-Float-Switch-For-Pool-Tank-/261328164676?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3cd85f5744 If the operation is the 'wrong' way as the one above then you just fit it upside down.

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I'm still not sure that I understand. If "it lets through current when the level is OK", why not have the low level switch feeding the coil of a Normally Closed relay? At normal coolant level, being energized, the contacts would be open, so no alarm. Then, when a low level occurs the power supply will be lost and the relay will close, thereby sounding the alarm. Or am I totally misunderstanding the system and the way relays work?

Mike

That's exactly what I did, and it works fine.

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There's hope for me yet! Thanks for confirming I'm not completely off my rocker - or should be confined to my rocker :wacko:!

Mike

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