[The magnet in mine doesn't move, so must be stuck in the low position? Banged on the unit, but it seems to stay in place... Thanks for the link.QUOTE=rgsaz;2052317]


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Discovery Channel approached me about doing a series called "Reed Switches through History" HO HO. I was about to install the new radiator, but the new one was faulty. The transmission cooling inlet and outlet were only 3/4" deep vs. the two inches required. Got an OEM one on the way!

"The reed switch is an electrical switch operated by an applied magnetic field. It was invented at Bell Telephone Laboratories in 1936 by Walter B. Ellwood. In its simplest and most common form, it consists of a pair of ferromagnetic flexible metal reeds contacts in a hermetically sealed glass envelope" from Wikiepedia.


What are you doing? Why aren’t you out in the garage, playing with a magnet and the reed switch, and posting pics?

Criminy, the suspense is killing us! [/QUOTE]

 

So what's the verdict? Is the stuck magnet the only fault? Perhaps there is a layer of sediment on the bottom of the reservoir. The magnetic float sank to the bottom (as designed) after the coolant level dropped due to the radiator leak. But maybe the sediment acted like glue, so the float stayed submerged after the reservoir was refilled. How about filling the reservoir with boiling soapy water? Maybe that would break it free. Worth a try, and the boiling water won't hurt anything.

Have you tested the switch by itself? Just hook up an ohmmeter and check continuity. Move a small magnet past the glass capsule and you should see the contacts make and break.

 

There is continuity when the sensor is placed in the unit. I'll give the boiling water a shot because the magnet seems stuck. Thanks for the reply and the idea.
Bob

 

The coolant tank is upside down and you can see the float stuck in the "low level" position. This is a look at the inside of the coolant tank showing the reddish float ring that contain a magnet to complete the reed switch circuit. It appears that my issue is with a stuck float ring. I was able to shake the tank to get the ring to move up and down, but as someone responded, I probably need to clean inside there.
Bob


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Thanks to everyone that responded to my question, especially to Don and Karl for all of the reed switch information..

After I finished installing a new radiator in my 2003 stype 4.2l non turbo with 117,000 miles, I refilled the coolant system with new fluid and then drove it for 10 minutes to check for leaks due to the installation. Thankfully, no leaks, fires or explosions! However, the "red eye of doom" on the dash still gave me the low coolant warning. I disconnected the electrical connection from the sensor and still had the alert. I then "jumpered" the connection and the alert disappeared. All this time, the magnetic float was stuck at the bottom of the coolant tank. Conclusion - "normally closed" is the no alarm position, which is the up position of the float. At some point I'll order a new coolant tank and drop it in.
Thanks again,
Bob of Arizona

 

As a side note I have just had delivered a new genuine jaguar expansion tank part no. C2C-41300 as my original is split and leaking.
In the advert it clearly stated: 'Excludes water level sensor simply swap your own across'.
However, when it arrived it did have the sensor fitted!
So that was a good result!

I will be installing the tank at the weekend.

Mellow