Solution for Truck with 12 Volt Accessory Circuit Not Active  

Ive tracked down all leads on my 7 way plug on a 2008 F350 diesel. The tail lights brown, left turn /brake yellow, ground white, E brake blue, rt turn /brake green and reverse brown /black all work as expected on my tester and the trailer. The 1 oclock position heavier dark orange should be 12v Aux that matches my heavier black wire on my puma unleashed trailer. But no power on the tester and trailer batteries do not seem to be charging. Seems straight forward but Ive looked at the fuse in the passenger compartment labeled for trailer tow battery charge relay coil and thats ok besides that also manages the brake controller which does work. I also looked at relay #56 in the power distribution box labeled for trailer tow and it is seated. Is there a way to test the relay? Is it common for this to fail? I dont see any wires loose under the truck leading to the plug. Any ideas for how to track this down would be helpful. Thanks.

asked by: Thomas R