Originally Posted by Malia20
On my 2017 FC20 there is a positive bus bar between the battery and the battery switch solenoid. Coming off this buss is a fused black wire that feeds the breakaway switch. In this configuration, the breakaway switch is not turned off by the standard battery switch, so if the battery is good the breakaway will always be ready.
I see. Thanks.
I knew there wasn't a pair in the battery box, and I've installed a battery disconnect switch on the black or - side. I'll need to keep the battery switch "on" while towing or else the brakes have no emergency power.
I'd do that anyway because with the batteries "off" the tow vehicle won't charge the batteries either.