MG TF 2004/2005 OEM Low Coolant Alarm - Wiring diagram, Owners Manual Page

LancsMGPaul wrote:

No I definitely have the check light when the key in in position II. It briefly illuminates in position II and on engine ignition maybe 3 seconds. Then it goes off and last night re - illuminated after 30 seconds when the water in the temporary coolant tank was released .

Then you have your system fully working as expected. Congratulations!

Thank you Roverlike and thanks for making me aware and helping me identify it. Much appreciated.  I just need to buy and fit the appropriate expansion tank. Fortunately I've very recently fitted Bruce's superb low coolant alarm so now have that in place , however , I will now also install a "factory" alarm to run in parallel.  Thanks again.