Guys, purchased a new trailer with interior lights. My 7 way on the truck for the hot lead to run the lights doesn't seem to be wired. Assumed that would have been stock. Anyone if them are supposed to come wired for hot lead or do I have to get that done.

OR, is the a trick like adding a fuse in the fuse box to solve this??

New 2019 F150 Lariat with trailer tow package...

 

Is it the hot lead missing, or is it one of the "one off" trailers? There are a couple of "standards" for how the 7-pin is wired, and you may have found one of the odd ones.

It's called 7-way traditional versus 7-way RV Standard. This is a good explanation: https://www.etrailer.com/question-153136.html

 

Trailer is just an enclosed sled trailer by ATC trailers. Truck seems to be missing the hot wire to run the interior lights in trailer. Checked with test light on trucks 7 way plug

 

Make sure you test it with the truck running. The hot lead on ours goes off when the truck is not running.

 

Is there a battery on the trailer? The truck won't output power to the charge wire without it. Lots of discussion on this, lots of guys are running a dedicated constant hot to bypass it. Unfortunately it's a function of the SJB.

 

Nope, no battery on the trailer. Just two LED lights on the inside that I want to work.

Was surprised this was not prepared on the truck.

 

The two led lights won't cause enough load to trigger the charge circuit.

 

Really, when I tested the post on truck with test light it didn't show any power to the post yet.

 

I didn't think the load was the issue. I thought the truck needed to sense voltage there (I.E. a battery).

 

My trailer dealer said sometimes on F150 they don't wire that plug for 12v hot. Said F250+ they come prewired.

Odd, owners manual show it, fuse box has a fuse but test light shows no power. May need to call the dealer to verify.

 

This goes back to the start of can bus protocol trucks 2011, the trucks do not have constant hot, the SJB will determine if it allows it or not provided the trailer is properly attached ( indicated by trailer connected message). The super duty trucks are not immune from this either, several recent threads on it and users adding a dedicated circuit. Also note if parameters are met the 12v will only become hot with the truck running, have you verified with the truck running?

 

Just today I have confirmed how the trailer tow module works for this.

I have a 2019 F150 Lariat with trailer tow package. The truck must be running and you have to hit the brakes which activates the 12V hot lead. At that point it will supply power to the LED lights in the trailer. If I turn the truck off or disconnect the trailer wire I will have to hit the brakes again to activate the 12V hot lead. This may become the new process on Superduty in the future too.

It was explained that they don't want to run constant 12V hot lead as it attracts static electricity and promotes corrosion around the plug. In addition, they said if you draw too many amps for the 12V hot lead that it will turn off until you reduce the level of amps being drawn.

I will actually test this tonight when I get my ride back. (also, owners manual never even mentioned anything about this)