I'd like some help please.
I'm after fitting a coolant loss sensor to my 300Tdi aluminium header tank.
The fitting part is easy.
I have a Range Rover pre 1989 coolant loss sensor part No PRC5077.
This sensor works using a reed switch.
When the reed switch is on and the level correct ,it will light an LED up but not a test lamp made from an instrument panel lamp.The light will go out when the level drops.
The reed switch is not powerful enough to trip a relay.
We can't find the Land Rover bit that the sensor uses to light the warning ligh.If anybody has that part number things could be easy.
I'm stiil trying there as well though.

So how do I get this light to work the other way.
I can cope with wiring diagrams and if told how I can put the parts together.

Any sensible suggestions welcomed.


Do you think I [or anybody else] would notice the light go off at failure time??Assuming I wired the LED up to be on all the time and off when the coolant level drops.


I eat rat poison
mike

I can cause trouble in an empty house

Are you sure it is a reed switch? In case you don't know, these are a pair of contacts that are ustually kept open by one of them being on a spring. re: http://www.maplin.co.uk/Module.aspx?Module...0switch&doy=1m3

Is it like a relay but use a permanent magnet which is brought close to the contacts instead of eltectomagnetic coil.


how have you wired up the circuit? What is supply to the contacts? How should this be wired? (i..e do you have wiring diagram vfrom manual)

I am very surprised you cannot get enough current through one to turn on a lamp - instrument lamps are typically a couple of watts, even a 3 W would need about .2 A (although that is ten times more than a LED).

Are you using a dropper resistor with the LED?

Also what relay are you using? Typical coil resistance of a signal relay is several 100 ohm; the high power ones about 100 ohm so if you are using the latter, then about the same as you lamp so results are consistent.

Have you tried using a signal relay? Something like this; 400 ohm coil resistance?
http://www.maplin.co.uk/Module.aspx?Module...a=relay&doy=1m3

I think you are better off wiring the indicator so it comes on when there is a problem; the other way round to what you suggest.

Mike,

If the reed relay can't switch anything above 50mA, use a transistor to amplify the current. Also, a transistor can be configured to reverse the signal. Another option - a SPDT sensitive relay. Third option - ditch the RR sensor and get from RS Components a Solid State Level Switch (parth No 477-4682)

Frankly I haven't a clue what the sender is.Ah !! I'm given this information...
The sender is a closed circuit.Relays draw 0.5 amp which is to high for the tiny magnetic reed switch inside the sensor.
I do know when you have it in the water and you lift it out there's a fair old clunk !!!

No resistror with the LED.The LED is 12 volt.

The whole problem is I can't find a wiring diagram anywhere,having that makes things easy.

Thanks anyway

I eat rat poison
mike

I can cause trouble in an empty house.
I'm off elsewhere later this morning.
Also I hope to be able to wreck the wiring loom that the sender came from.
If I could identify the wiring and the warning light unit that triggers the light,things would be easy.

The relays O2,s speced only pull 37.5mA at 12V which should be quite low enough to safely switched by the sensor.

Use the normally open or normally closed contact to get either on all the time then off when the level drops or lit up when the level drops, needs to be fed via an ignition fed source so its not on all the time though.


Cheers

A mate of mine wrote a very handy bit about this mod - have a look here: http://www.ep90.com/index.php?id=67 includes the part # of a suitable relay although 02GF74's suggestion at 37.5mA should be fine, or an LED.

Thanks.
I was directed to that site by a friend.
I'm having fun getting that relay,which is why I've tried another tack !!!!

You wouldn't think that my eldest girl and her husband are one a hardware engineer and the other a software engineer with me struggling like this.

I eat rat poison
mike

I can cause trouble in an empty house !!!