Originally Posted by goducks
So if your trailer starts swaying and the sway command kicks in and then you hit the truck brakes, which activates the brake controller, which then activates all the brakes on the trailer, what's the point of the sway command? Or if the trailer is in sway mode does the sway command override the TBC? Or vice versa. Thus the compatibility issues.
All the brake controller does is supply voltage to the brake mechanism, which actuates the brakes. From the trailer's perspective, I don't see how any brake controller is any different than another. There's either voltage on the brake line, or there isn't.
The more voltage supplied to the brake, the harder it is applied. My guess is that Sway Command just actuates whichever brake is required to bring the trailer straight again. If the brake controller is actuated at the same time, presumably it would be sending higher voltage, and effectively "override" the Sway Command's input.
The only thing I can think of is if the brake controller will act adversely in the presence of voltage on the brake line that it didn't generate. Maybe that's it?
From the manual:
"Note: In the event a tow vehicle brake controller detects a fault after Sway CommandTM detects a sway event, manually activate the tow vehicle brake controller a few times to clear the fault."