Someone help please! My truck was perfectly fine when parked in a parking lot, came out about two hours later let her warm up and started down the road. Was still acting fine for a few miles than started acting up around 45-50 mph. I have a trailer brake and the light for it won't turn off. Also brake lights and blinkers stopped working. Fluids are fine. Any clues as to what might be wrong??

 

Check the in cab fuse panel for blown fuses for the turn and stop lights. Also check the wiring to the trailer plug for damaged wires that may be letting circuts cross feeding telling the brake controller there is a trailer hooked up.