THERE ARE LOTS OF CAUSES FOR THE FAILSAFE:
FAULTY INPUT SPEED SENSOR
FAULTY OUTPUT SPEED SENSOR
FAULTY SOLENOID OR SOLENOIDS IN VALVE BODY
LOW FLUID CONDITION
FAULTY RANGE SENSOR
TORQUE CONVERTER SLIPPING
INTERNAL MECHANICAL FAILURE
INTERNAL HYDRAULIC LEAK.
THERE MUST DEFINETELY BE TROUBLE CODES STORED IN MEMORY ASSOCIATED WITH THIS CONDITION, IF YOU CAN HAVE THE CODES READ AND LET ME KNOW WHAT THEY ARE, I CAN TELL YOU WHAT IS THE CAUSE AND WHAT IS THE REMEDY. I WORK IN A TRANSMISSION SHOP FOR THE THE LAST 14 YEARS.
BISMARK.