I believe the Lariat has a different message center on it then my FX4.
To work mine you push in the trip button, start the engine, let go of the button with it says test in the readout. Then to scroll through the info you just keep pressing the trip button

 

Yeah - I have the FX4 - I think the Lariat is done differently - the info on the message center in the owner's manual is geared towards the Lariat it seemed. Maybe try looking in there.