Originally Posted by Kardon
My wiring on my tow vehicle (2014 Dodge Grand Caravan) is no longer working. . . . He found a black wire that he could not see where it went to (any ideas?). . .
That sound suspiciously like a missing ground wire. An open ground can cause bizarre symptoms. You should have a connection diagram for the 7 pin trailer connector make sure the wire connected to the ground terminal on your vehicle is solidly connected to the chassis of the vehicle.
If you cannot see where this black wire is connected, you can measure it with your new multimeter. Use the Ohms scale and measure between the wire and the vehicle chassis. Be sure to find a spot on the chassis that is free from rust and paint
. If the black wire is grounded, it should measure only a few Ohms.
This is pretty basic electricity. I agree if this is confusing your mechanic, you need to find a new one.