Kit Carson wrote:
Check for a bad ground connection.
^^ likely culprit... if you connect a booster cable between the truck and the trailer to a good grounding point on each does issue go away?
OP your suggestion to have someone with a properly functioning tow vehicle plug in to your trailer is what I would do...
We do like to "do it my own way my own self by my own self" ... so jacking up wheels and taking apart stuff is ok too...
But like you said I would start by figgering out if it is the truck or the trailer...
