A couple of days ago my coolant warning light came on which surprised me somewhat as I regularly check the level. When I got home and checked the level it did require topping up - but not much and not enough I would have thought to 'trigger' a warning light. After topping up however and switching on the engine, the light did not appear.
Today however, on a very sort trip (a couple of miles or so) the light came on again. Back home and a check of the level revealed no loss of water although I did manage to get a splash of water into the tank, but nothing more. The light however has remained lit.
There is no sign of any water on the floor or around the engine area even when the engine is running so I'm thinking it may be a faulty warning light.
Has anyone any experience of this happening and can give me any advice? Faulty sensor or something? If this is likely, then where is it situated?
Any help or advice appreciated.
Thanks.

 

The sensor is a long thin probe that pokes up into a dry chamber from the bottom of the tank. It is secured by a snap connection that can become loose. Look for the electrical conncetor in the bottom of the resevoir and push the probe back up into the tank. If it has not fallen out, then I suppose you have a bad sensor. More likely, its just loose.

 

Thanks for that, there it is is! Pulled it down and out of the 'hole', undid the connection and sprayed it with switch cleaner/lubricant and reconnected the electrical connection wires.
Now it won't go back up into the recess! I can't of course see it, just feel it, but I can't 'see' how it fastens there as when I push it upwards, it just falls back down. Has something else come off perhaps which secures it?
I may have to remove the plastic tank to see things better. Is this as straightforward as it looks? That is, just disconnect the hoses and remove it from what appear to be rubber bushes? I'd rather not do this of course, but if I have to I will.
Finally and as a matter of curiosity, how does this sensor 'sense' the level? It appears to fit inside a recess which is and has to be waterproof to the outside, so as it doesn't actually touch the water, how does it work?
Thanks again.

 

Use a [small] mirror?

 

Great idea - thanks. Now to find a mirror to smash into smaller pieces!

 

Well I'm a bit stuck now really!
I can push the sensor into its hole and even holding it in place with my finger, the dashboard warning light still illuminates. I just can't get it to stay in place, nor can I see (now with the help of a mirror!) how it is supposed to stay in place. There is nothing on the base of the expansion tank around the hole which could be described as any kind of connector or fastening. All I can see is the hole!
What now concerns me is how I will be able to fix in place a replacement sensor, assuming my current one is faulty if there's nothing to attach it to. Glue it?
If I unplug the connecting wire from the sensor, the dash light is still on, also I can't locate any dedicated fuse for the warning light to switch it off.
Is there any way to test the sensor?

 

All good questions and observations!

The sensor is probably a reed switch rather than a hall effect, since it has two wires. I am pretty sure there is a magnet on a float around that "post" inside the plastic tank. So when the magnet falls too low, the switch comes on or off. I do not know if the switch is on or off for OK, but you can test to be sure the switch is the fault. Just unplug it, then jumper the rwo pins on the connector. One is ground and the other is the sense circuit. The light should change state as you connect and disconnect the wires.

I don;t remember exactly how the probe clips in, but it is some kind of snap molded to the parts. If it is broken, you could epoxy it in. The float might be stuck. Look into the tank and see if you can see whats happening.

Good luck and report back/

 

I got a similar warning on my dash that turned out to be a faulty coolant level sensor at the top of the reservoir . We replaced it and no more light since then

 

I would have thought the more logical place for a sensor would be towards the bottom of the reservoir not at the top, but as you say yours is at the top then that's obviously where it is!
I think everything indicates a faulty sensor.
Thanks for your advice.

 

Thanks for the good wishes. The idea of jumping the pins did occur to me but I was concerned it might short something and blow a circuit somewhere. As you advise it though, I will give this a go.
Can I have your personal bank details please in case something goes wrong? PayPal will do also!

 

Seriously, that is always a concern on electrical circuits - that you can do major damage by jumpering connections. Frankly, I am amazed sometimes by what people report theyhave done while monkeyiing around- and often the car circuit protects itself.

Obviously, you are on your own on this, but I will vet myself that I am an electrical engineer and I looked at the schematic carfully before I gave that advice.

 

Ooops!! Before I read this, I took the risk and jumpered the connection. I thought the worst that could happen would be to blow a fuse (?). Anyway, made the connection, crossed fingers, held breath (a technique which has served me well over the years, barring a few accidents!) and switched on the ignition. All dashboard lights came on as usual and after a few seconds all went out including the coolant light.
Until if/when I get a replacement sensor, it will do me.
Thanks again to all for the advice.

 

Do remember that these engines are pretty bullet proof except for overheating. FIX THE SENSOR as soon as you can.
Good luck- glad to help.

 

Why worry and fuss? Replacements available:

https://www.jaguarforums.com/forum/o...e-smoke-60274/

 

Well... he was trying to do what lots of folks do not- diagnose the problem before spending money on what might not be broken.

 

No offense nor ridicule of the methods thus far employed intended, Spark/Biff...just a failed attempt at bringing some humor to your efforts.

In the none too distant past I had the pleasure to work with a chap who was frequently referring to having "let the magic smoke out of..." various and sundry electronic black-boxes, so I was tickled-pink to find "Replacement Smoke!" but also surprised the packaging didn't make the "magic" claim....

 

aholbro-
Replacement Smoke, huh? I bet we could get rich with that stuff . Most of the smoke iI have let out over the years has been danged expensive!