When is the last time you removed the hubs in your toy hauler and inspected the brake magnets and wiring to each... that’s where I’d go considering the age of the unit..l
We owned a 2006 and 2007 Aftitude,... good units...
The brake magnets are all wired in parallel and feed via one set of wires ... this should be easy to isolate and you can disconnect each magnet at back side of hub and do a quick resistance check of the brake magnet to verify its within spec
Should measure around 3.2 to 3.5 o(ms on each magnet when measured one by one
