brake controller feedback with flashers on??
 

ok, my 95 started getting an overload code on the prodigy brake controller. trailer place tested it and said the brake controller is working fine, its something in the truck wireing. when the flashers are on, and the truck is running (or ignition is on, and only when the ignition is on) it will apply voltage to the brake controller (around 1.5 volts) and apply the brakes. it will show this with or w/o the trailer so that eliminates the trailer. trailer shop said this has happened 1 other time with the obs truck but they forget how they fixed it! any ideas what to even check??? i'm no wiring expert and don't even know what to check...thanks