Hi All,
How does one check the coolant low switch to determine if it is faulty?
Thanks,
Mike

 

Just curious, what makes you suspect it's faulty, is it going on all of the time or none of the time?

 

The coolant low light won't go out. I recently removed the radiator, had it vatted & pressure checked. When I reinstalled it the light came on & won't go out. There are no leaks.

 

Might be some air trapped in the system. You can "burp" it by hand to speed the process using the top radiator hose with the cap off the expansion tank.

If that seems to help, there is a bleeder cap on the thermostat tower to get it all out. Just be careful, the plastic can be fragile.

You can manually lift the float arm inside the expansion tank. It is over in the rear corner of the tank toward the center of the engine bay. Lift it up gently with a long screwdriver or rod to see if the light goes out. The floats go bad and the arms like to stick. Do a search, lots of threads on this problem.

There is a sensor that mounts on the bottom of the tank. Check the connection.

Lastly, or maybe first, is there enough coolant? It should be filled to just the bottom of the expansion tank opening.

 

What Mike said. Just one footnote ...

When you raise the float manually, there can be a delay of several (~10 ?) seconds before the "low coolant" light goes out. Fooled me a few times at first.

 

Hi,
Me again. Does anyone know the correct procedure for burping the cooling system. Do you do it with engine running hot or cold? Does thermostat have to open? I am hoping this will quell the dreaded Demon "Engine Coolant Low Light".
Thanks

 

Remove the thermostat tower cap and reservoir cap and squeeze the large upper radiator hose . . . cold . . . not running. Top up with coolant.

Some respected techs recommend clipping the 'giggle' valve off the thermostat which will more quickly allow air to escape which ends up in the reservoir.

The magnetic float fails or at least causes a lot more problems than the reed relay sensor mounted on the bottom of the tank. The sensor is also very fragile and should not be removed without removing the tank so that you can carefully pry it out. The last OEM tank purchased, of 5 on a couple cars, from Jaguar had a sealant semi permanently attaching the sensor to the tank.