300Tdi Coolant Level Sensor

[van_kerr]

I think the last comment is valid ...... Anyone willing to make and sell a few of these ?

Put me down for one ................... please.

[discoverytdi]

me to please

[Phil Wilson]

Tim
I am in grave danger of getting out of my depth here....but I am going to be bold and ask the question.

I wanted to understand your circuit, so I built it in a circuit simulator (probably the cause of my question). Incredibly it A) works and B) makes sense to me (amazing - I know).

My question comes from the extra test circuit section. On my simulation I did not have an opto-isolator to play with, so I used a simple relay to prove the point of the circuit. The 680ohm resistor on the test circuit is too big to stop the relay from switching, in fact I needed to use 300ohms or less.
Is the problem because I was using a relay and not the opto-isolator, or is the problem "real"? The relay in my circuit needs 5mA to switch...presumably an opto-isolator needs around 25mA and is therefore a lot more sensitive and the 680ohm is fine to use?

Cheers mate.

[:)]

[steve:h]

I think I can hear the cogs grinding in Phil's head from here!



Steve.

[Phil Wilson]

Steve - I need some Evo2 in my head!

Tim - Somehow (and I am not sure how) I am understanding all of this, with a little bit of googling for added information! Also I am finding it interesting....which is also odd for me!

Thanks as ever mate.

[Disco Sev]

Hi all,

Been following this post and can't help thinking "There must be an easier way."

So I bought one of the tank caps and had a play. Turns out that the top just 'pops' out as it is only held in place by the friction of an 'O' ring.

Then going back about ten pages simply bypass/replace resistor and you're left with a very simple circuit involving nothing more than a SPDT relay and buzzer/LED of choice.

Oh and I don't even own a TDi

Sev

[:)]

The grey top where the connectors fit is a separate piece and should come off. I tried to remove this on my switch following Don's example, but I was unsuccessful even a bit of gentle prying only left marks in the plastic (it certainly is held in with a lot more than just the friction of an 'O' ring). As I wish to use mine, I have stopped here!

We have learned that Siemens VDO make different versions of this cap switch. I'm sure there will be a version for another vehicle which will allow it to be used directly with a relay, or others may be able to modify the Range Rover one (bypassing the resistor) if it comes apart.

If you do use a reed switch to drive a relay coil remember to include some fly-back voltage protections (either a diode or resistor across the coil) so that the energy has somewhere to go. Failure to to this could damage the reed relay contacts.
--
Tim.

[mr vimes]

i,d like to ask a silly question of you clever automotive electrical folk out there but could you run a couple of wires in parallel from the break fluid level sensor to the filler cap on header tank so that if you see the break fluid warning light come on you know straight away its one of two things...i.e break fluid or water level...not very elegant perhaps but a temporary get you by until you can make it more permanent...all you would need is a couple of bits of wire and some spade connectors...or have i missed something...sorry if i,m being a bit dim here but i have a blind spot when it comes to diesel engines, electrics and women....especially women

[Phil Wilson]

Well I for one am going to through caution to the wind, and try to make one. I have priced the leccy bits up on RS - which come to £12. The cap we have already found to be £40, and I like giving money to Beamends Spares anyway...so they can have some more.

So Tim, I solder it all together component to component, then shove it in the potting box, then pour the epoxy on it and wait for it to set? Do I need to get a power supply to test it, or could I use the cigarette socket on the wagon to power it for testing? Then I suppose it would best live behind the instrument panel so that I can hear the buzzer and see the lamp....but where should I take the power source from, and where is the best earth for it?

Fortune favours the brave and all that!

[mmgemini]

Right for the third time........Will I be able to post this I wonder ??

Phil.
Earth.I would use a ring terminal to which ever instrument already had an earth fitted to it. That should be all of coures

Live.Any easily got at White ,Green or Light Green wire should be live.The greens are better 'cos they're fused,or should be.

Mine will eventually live behind the instrument panel.Double sided sticky taped to the bulkhead.

What epoxy I'm wondering.

[Phil Wilson]

[Disco Sev]

[mmgemini]

[SimonWH]

For all those (like myself) who would like to get something like this for their own vehicle but don't know one end of a soldering iron from another . . .

It only makes it viable for Tim to make them if he can make these in larger quantities rather than have the hassle of making one-offs for people so we have agreed to pay to have a batch of these made up and will add them to our store.

We'll also offer them with or without the required header tank cap. Again it's easier (and probably cheaper!) to buy the caps in large quantities rather than single items from your local LR stealer.

Watch this space!

[neil_gh]

I had the same problem with the high resistance of the level sensor but over came the problem but using the “lights on” alarm from a Vauxhall car. The part which looks like a relay actually has a buzzer build into so you don’t need any other parts and mounts in a standard relay housing which can be obtained from vehicle wiring products (www.vehicle-wiring-products.co.uk). The alarm has 3 connections, one a power feed from the lights to indicate when they are on, one which is earthed via the door to indicate when it has been opened and one which is supplied with power from the ignition to stop the alarm activating when the ignition is on. For the alarm to go off there must be power from the lights, the door must be open and the ignition off. I therefore wired it up for the level sensor by

A. supplying power from the ignition to the connection which normally has power supplied when the lights are on,
B. permanently earthing the connection which is normally connected to the door switch
C. supplying power to the connection which normally only gets power when the ignition is on via the level sensor

The alarm now has conditions 2 of the 3 conditions to set if off (A & B) but won’t go off while C is supplying power which it is getting via the level sensor. When the level drops the coolant level sensor goes open circuit and stops supplying power to the alarm making the third condition i.e. the ignition is not on.

I did fit a push switch between the level sensor and the alarm which was normally closed but goes open circuit when is was pressed to simulated low level so I could check the system without lifting the bonnet or even when I was driving along.

I fitted the alarm about 3 months ago and it was working great until my Defender was stolen last week. I did find that if you had to brake sharply the alarm would go off for a fraction of a second as the sensor is near to the rear of the expansion tank and the water must all go to the front. The alarm which cost me £2 from the local scrap yard has Vauxhall part number V0090464777 and is fitted to lots of their models. The relay housing was about a £1 and the level sensor £30. The alarm will fit to a standard relay mounting so if it ever fails it is just a pull out push change and it can be easily heard over the engine noise.


Neil.

[:)]

This is another interesting solution, I suspect the buzzer has a transistorised input so needs very little current.

While testing I tried getting the cap switch to drive a piezo-electric buzzer directly - which worked fine due to the low current demand. However, I didn't pursue this line as I felt you needed an indicator lamp as well to indicate the source of the audio alarm. I have multiple inputs to my buzzer and I find it useful to know which one has triggered.
--
Tim.

[dpcwright]

Neil
Could you advise us of which connection goes where on this relay - my relay has connections marked 15,30,and 31b
Thanks
David Wright

[reedx]

David

This may help you with the terminal designations.

http://www.reedx.net/landrover/mods/boschtermdefs/index.htm

[neil_gh]

David,

The connection numbers on the relay/buzzer from memory are

31b = earth
30 = supplied with 12v when ignition is on
15 = supplied with 12v from the level sensor (other connection on level sensor is supplied with 12v when the ignition is on)

Neil.

[dpcwright]

Gentlemen,
Thank you both very much for your help - and it works! All for the princely sum of Two Pounds.
There lots of electronics in this little box but I can not see a number on the chip.
David Wright

[Tim.]

The kit available yet? Needs to have very good instructions as i have a severe phobia of electrics....

[SimonWH]

Hi Guys, Tim has sent us an example of the Coolant Level interface (thanks to Royal mail for delaying it's arrival for a few annoying days!)

First impressions are that I am very impressed!. It's is very well made and the accompanying instructions and wiring diagram are very well written and simple enough for technophobes to understand (if you can wire a plug you'll be able to fit this!!)

As with everything we sell in the store we need to check it out ourselves and we'll hopefully be ordering the first batch very soon. We'll also get in a supply of the Range Rover caps.

Obviously we'll let you know when they're all ready to ship

Cheers

Simon

[naughty lee]

having had a very lucky escape after spotting a leak and discoverying the dreaded P gasket had failed before losing any great deal of coolant i have often pondered of ways of some kind of early warning system.
.
I was thinking along a more simpler line involving a modified fuel tank sender unit and a bulb/buzzer
.
there is no taking away the fact that the work done on here is great and well done for it.
Its whether or not the average joe soap can knock one up and more importantly wire it up, if a bulb comes on whilst off road or driving harshly thats to be expected, however if you are trundling along gently at 50 and it comes on, its warning enough for you to pull over and take a quick peek under the bonnet to see if there is a large repair bill in the making!

[Tim.]

Just a question... How does it know when water is lost... eg during driving. Is it a sudden drop in pressure? As pressure will change as temperature. Landies dont usually dump their coolant while parked do they?
its propbably in the plethera of text but a short and sweet answer would be good!

[Phil Wilson]

If you are asking about the RRC header cap, it is a floating switch. When the coolant level drops, the float drops with it and magnetically flips a switch.

HTH

[Tim.]

If its the RRC cap that is going on ours then all will be well.
Anyone got a pic of this magic cap?
And what interface will the warning be? A light, buzzer or what? I am quite experienced in whipping my instrument binaccle out no problem...

Full o questions today eh!

[:)]

There is a picture of the switch on page 1 of the thread. You can just make out the black ring magnet embedded in the white plastic float. The reed switch is inside the black core and operates when the magnet is in close proximity. When the float falls away the contacts open, which is fail safe as the alarm would also sound if there is a bad connection to the cap switch.

Copy of picture on previous page:

--
Tim.

[:)]

[Tim.]

Will the buzzer/light be in the kit? There will be a kit wont there lol!
Will have a more thorough read of the thread when i am less tired. I'm just looking for easy answers lol! Cheers Tim

EDIT after reading thread...

Has the depth of coolant issue been resolved yet?