The mXT143E Xplained has an optional routing possibility for the LED backlight control. The alternative signal is pin 2 of the header J4. To change to the alternative location, it is necessary to disassemble the display module and de-solder the existing 0-ohm resistor shown in Figure 1 and solder it back on to the alternative footprint. It is also possible to just add a solder joint between the two pads to get a new connection.
Figure 1. Alternative
Backlight IO
