1998 Jaguar XJ8 clearing cpu to clear trans problem

In my jag. i got a check engin light..than the trans.light came on showing incorrect gear and than trans.fault. i have disconnected the battery but i cant seem to get the engin light to go off..I think maybe the cpu.s not telling the trans to work right..it acts like a stall converter..does not want to go and about 2000 rpm it locks up..how do you read the codes in this car..thanks for any help