The electrical service manual will take you right to the cause but "input High" usually means the trigger or input sensor wire/connector is open or has an intermittent connection. Inputs to modules usually have what are called "pull up resistors" in them which will force the input "hi" (+5v) when nothing is attached to them.
In your case, an input would mean something like the vehicle speed sensor (an input) was disconnected electrically (even for a second) which would force the module input to go "Hi" as a result of the pull up resistor.