You can see the light position on the dashboard lower right..
Not wanting my Td5 coolant loss to happen undetected which is a very real threat, I wanted to fit a gauge that would mitigate the issues of having a low coolant level.
Using a coolant low sensor on the upper radiator hose with the correct wiring, we can create an alarm that we can wire up to a dashboard warning light that lets us know if the coolant level drops before it becomes a bigger problem.
Where i bought my kit
You can see here how you fit
CHE OVERLAND Land Rover Defender 90 Td5 
I was thinking about grabbing one of these, this video has convinced me 100%!
Late reply zak, i worked for me fine , it has giving me a peace of mind and a secondary check
It works fine , the buzz is heard and with ever Ignition a check is done and heard , small investment peace of mind