Jeep brake lights not working/Blue Ox system

Take a test light and turn on the left turn signal with the toad cord plugged into the back of the MH test each plug hole to see if your getting power to the toad should be one of the two lower plug holes if the bar for outside of the plug is on the top. Then do the same with the Right turn signal. If they work the problem is on the toad side could be just a ground problem.

All really good advice so far. But, even if it was a fuse, why would BOTH brake lights go out at the same time? About 99.99999% of the trailer connectors on 99.99999% of the motorhomes/trucks/space ships etc. have:

1. Right turn/brake
2. Left turn/brake
3. Tail/marker
4. Ground

.... And so on. I can see one side (brake light AND turn signal since they're the same signal at the trailer connector) but, both at the same exact time? I'm by far, not the sharpest tool in the shed so, I could be really blind as to what you're suggesting. I do know about the pin thing where, those pins collapse a bit and, one needs to get into them and pry them apart just a scoch so they make a better contact with the female counterparts inside the other half of the connector. I had a problem just like that in setting up a buddies Jeep for towing. Took a bit of head scratching on that one.

Anyway, it will be interesting to see what the OP finds out is the problem.
Scott

What type of connector one MH? What type of umbilical cord? Any adapters?

check the male end of the cord to the jeep,
as you may have to pry the prongs open a little
You should be able to see if they are pressed tight, there should be a small gap

Yes, on a Ford chassis.
Verify with a meter or test light to see if you aregetting power to the turn signal locations on connector.
Does the turn signals worK? If yes, then not likely to be fuse but possible.

Does it make sense for it to be a problem with the fuses?

Ford chassis has separate fuses for the trailer connector.
Look in chassis manual for exact location. Believe under hood driver's side.