Hey man i have an 89 legend sedan and mine keep on coming on also, usually right when it is shifting in 2nd gear cuz mine is an automatic. i'm not sure what it is but i think it is a bad sensor. all i know is that it will cost $50 to get it looked at and then it will probably take another $350 to get it fixed. I have been driving with mine on for the last 25,000 miles and it hasn't bothered me yet. so you should be alright till you fall into some money! good luck!
89 legend sedan
2 12" kicker subs
500 watt orion amp
you also might want to be cautious, I had the same problem, and I of course ignored it adn one fine day in an emergency braking situation (cat in the road (I LOVE kats)) my brakes just locked up totally I skidded like 20 feet and hit a mail box
just a heads up