Why Dual Sensing?
Think about it.
If the system works ONLY on a brake light signal from the Motorhome then the slightest touch of the Motorhome brakes will activate 100% of the towed vehicle brakes. There is no proportionality, the towed vehicle brakes are either ON or OFF. Very binary I/O and unstable!
If the system works ONLY on a signal from the G Sensor then you will at least get 20% braking with 20% braking and 80% braking with 80% braking etc. But if you are going down a long hill or mountain pass under Engine Braking then the “trailer” will sense this and apply its brakes. Soon the towed vehicles brakes will overheat and you could arrive at the bottom of the hill with smoking, burnt out brakes!
Only with Dual Sensing do you solve the problem. Under engine braking, although the G Sensor is sensing deceleration, the brakes will not be applied until you touch the brakes in the motorhome and provide the second signal to the system. Under light braking on the flat a 12v signal may be sent to the brake system but with little or no deceleration sensed the G Sensor will keep any braking safely proportional.
Simple, No Fuss, No Hassle, Cool Brakes!