Backlight dimming Innolux at065tn14 with vs-ty2662-v1 (PCB800099) LCD driver board
I was able to get this board to dim the backlight by using a filtered PWM signal attached to the FB pin (see option no. 3. in the PT4103 documentation). I've cut the feedback trace close to the PT4103 and soldered a wire directly to the FB pin and to the right side of the 1R0 resistor near the PT4103. 

By using the suggested circuit for a filtered PWM signal in the PT4103 documentation i was able to get the backlight to dim without any problems by using a 10Khz PWM signal and changing the dutycycle.