Quote:
Originally Posted by liveoakal
We blew the 40amp fuse on our trip across the country last fall. I noticed the brake controller was showing a ground fault as we drove along and that day I discovered the blown fuse when we pulled in to camp that afternoon. The cable from the controller to the hitch (which I installed) had drooped down and became abraded by the driveshaft. I was glad to find that the problem was so obvious and spent an hour under the truck splicing the cable and zip-tying it out of the way. No problems since then. We were so fortunate to find a fuse at a general store in the small town about 10 miles away.
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The brake controller in you vehicle gets its' 12 VDC power supply from the tow vehicle .
The wire going from the brake controller to the trailer brakes also gets its ' 12 VDC power from the tow vehicle through the brake controller.
If the 12 VDC power wire from the tow vehicle to the trailer brakes is shorted out or grounded a fuse in the vehicle would blow , not the trailer battery fuse.
The only time the trailer brakes are powered from the trailer battery is when the breakaway switch is activated.
If the break away switch was activated , your trailer was connected to the tow vehicle and the wire from the brake controller to the 7 pin receptacle on your vehicle was shorted out then the trailer battery fuse could / would blow .
The above statements are based on the assumption that your brake wiring conforms with standard wiring procedures.
Your brake controller looks for a resistance reading through the brakes magnet coils . If it see zero or too low of a resistance it will show that there is a ground / short circuit . If the brake controller reads high resistance or an open circuit it will show no brakes or brakes disconnected. If you leave the engine of your vehicle running , unplug the seven wire trailer plug from the vehicle , you will get a warning light on your vehicle dash or your brake controller telling you that you have lost your trailer brakes
( This does nothat apply to all vehicles )