No Brake Lights? It's a puzzle I promise

So, the title got you here... let's go

Pre tripped truck and this junk container and all my lights worked prior to leaving the yard. I checked.

35 mins down the road... level 1 inspection... I got a sticker and a pull over there so u can fix the trailer brake lights.

Pulled over, my company sent out roadside... roadside got there and the trailers wiring was a nightmare. The female plug on the trailer had bare wires touching negative an positive after the guy disconnected it...

We discovered my tractor is not putting out a brake power to power the trailer brake lights.

Tractor brake lights work, every single light works including hazards, blinkers, markers etc...

Checked a fuses an relays...

Where do I go from here ? What do I look at ?

- #sadvolvodriver

 

The road service guy had one, I swapped it out an it did not fix the issue

 

I checked and replaced it, I think it was F36 or F37. I replaced several fuses that were related to the trailer. I'll double check tomorrow

 

Yes, they started on some BS. Saying oh it could take several hours to check this an that...I'm a local contractor so I called dispatch an had someone come get the trailer and I bobtailed back to the yard.

I did change several fuses... including swapping the relays around with no luck.

The service guy said there might be a pressure switch in the dashboard an wanted to take my truck apart an I told him no....he was also screwing around with a relay by my firewall near the air connections an when he did the engine turned over an I told him stop... ...

I am very mechanically inclined, and was absolutely dumb founded by his ...troubleshooting methods ...first thing I checked was fuses an pig tail...and hooked to a different trailer when I got back to the yard

 

I user that exact diagram to find no power coming from the bottom pin hole