I tow my H2 behind my motorhome when I travel. I use a Brakebuddy for supplemental braking. When I plug it in it has power but apparently not enough for the compressor to come on and build air pressure. I know it has power because a light will come on. I know the brakebuddy works because when I plug it into a plug in the motorhome the compressor kicks on like it should. Any suggestions?