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Since there is no fluid dipstick it is difficult to check the fluid level and condition. You need to warm up the transmission and remove the center small allen plug from the pan drain plug. If fluid flows out then it is full. You need to do this on a level ground or lift. To fill the transmission remove the 8mm allen plug from the tail housing and with a hose or suction gun fill the transmission. I recommend the Jag fluid but you can use Ford Mercon V.
could the warning light indicate anything else