Truck Repair: 2000 FREIGHTLINER CENTURY, automatic shift, light flashes

Question
NO ONE CAN SEEM TO FIND MY PROBLEM I HAVE AN AUTOMATIC SHIFT FULLER SERVICE LIGHT FLASHES WILL NOT DOWN SHIFT OR UP SHIFT IT WILL STAT OFF IN HIGH OR LOW IN REVERSE IT STARTS IN HIGH GEAR AT ABOUT 8 MPH  IN DRIVE STARTS IN 6 GEAR ANY ANSWERS

Answer
To check the faut code you have to do this:Turn key to ON position.Turn key off & on 2 more times in 5 seconds ending with the key on.That is for ACTIVE codes.For INACTIVE faults:Turn key off & on 4 times in 5 seconds ending with key on.The codes are 2 digit codes.Flashing pauses are separating the fault codes & they will automatically repeat after all codes have been flashed out.To clear codes: Turn key on then off & on 6 times in 5 seconds ending with the key on.Let me know the codes.