Touch Panel
The panel touch sensing system consists of 10 horizontal and 20 vertical infrared beams. Touching the screen blocks both a horizontal and a vertical beam. Every possible touch position is shown on this diagnostic screen. Touching one of these areas should cause its color to reverse, and sound a "beep". If any areas of the screen either don't respond, or respond at some other location when touched, then replace the display unit. The "Display" diagnostic under in Unit Check provides an additional method to determine if one of the infrared sources or detectors is bad.
NOTE:
Direct sunlight can affect this test by falsely triggering the infrared detectors, so perform this diagnostic inside or in a shaded area.