1994 Jaguar XJ6 94 Jaguar XJ6 transmission failure light h

Hello I have a problem that wont go away for over a year my transmission light will come on and go off.
i can start it in the morning and the light would be on then 2-3 min later I herd a relay click the light turned off and the transmission would be able to move but with the light on limp mode this is my question what type of error is the light suppose to light up for I don't want to know what my be wrong with my car just what dose the light on mean I have changed the transmission computer with a new unit with no diff. Also I noticed if I push the car to go fast this will make the light turn on also and im talking flooring it. Somebody told me it was the T converter so the had me power brake it and I will say the tires did spin faster that I would have thought but 10 sec into that the light turned on. Some days I will never turn on maybe even a week no water any were allready checked 4 times help me please thx