The transmission light will be on when you are not moving, there is a pump on the right side that only turns when you are moving or in neutral and the hydo. is forward. Is this a hydro. or var. belt drive speed. The belt will run when the clutch is out and the tran. pump will be working, if that is what you are looking at then have them check the pressure at the sender, if it shows ok then the sender is bad or something with the elec. system..