Hi,
It is very possible that the height adjustment of the trigger switch underneath activated by the brake lever is slightly out of alignment. More often this involves a few turns of an open wrench on the lock nut of the switch.
Should you be interested, a repost of my response to a request for bypass of this model.
based on safety concerns. the DVD won't work if brakes are not engaged.
The sensor for the enabled/activated brakes is the yellow/blue wire.
To bypass this model would mean grounding the brake wire would allow DVD
playback. There is a little trick to make it work. It should start
first as +12 before it should be grounded before the DVD will play
hence a DPST switch would be required, not only grounding.
This is better explained
here. Should you be in need of the manual, it is available
here.
Additionally and a friendly reminder, in some regions, it is not allowed to view a DVD movie while vehicle is in motion.
Hope this be of help/idea. Pls post back how things turned up or should you need additional information.
Good luck and kind regards.
Thank you for using FIXYA.