I have a 2014 F 450 and today one of my trailers will not engaged the brakes and it is saying on the display that there is no trailer connected
I can not engage the brakes manualy with switch.
I have running lights , I have brake lights I have hazards lights and turn signals
The brakeaway switch is not engaging the brakes when removed, I hooked up to another trailer of mine and it recognized and acknowledged being hooked to a trailer . So... I know it is something with the trailer but does anybody know what wire I should be look ing at on the trailer?

 

Hope this helps

 

Typically the brake wire is blue but that's not the case 100% of the time.

 

If it's using a standard cord with a molded end it will be the blue wire, if it's just a hard wired plug it will be the terminal marked blue. I've had the same problem with my enclosed trailer and rv trailer and it was corrosion in the cord end. I bought a replacement end from NAPA, they have better contact area then the molded ones.

Denny

 

What wire tells the truck that there is a trailer connected ? I test lighted the blue wire and I have power

 

This is the key right here. You got it right that it's not the truck, it's the trailer.


Sounds like a bad breakaway battery or bad/corroded connection to the battery. Recently ran into that very issue with one of my trailers. Swapped the breakaway battery and all was well. Just an idea to check.


Faulty trailer wiring will also cause the same issue.

 

From the Workshop Manual:


"Every 4 seconds (when not braking) the TBC module sends a voltage pulse to pin 3 of the 7-pin trailer tow connector to determine whether or not a trailer is connected."

Pin 3 is the lower left-hand (lower driver's side) pin. It's the blue wire and controls the brakes.


However, as I said in the previous post, even a breakaway trailer battery can cause the "TRAILER DISCONNECTED" message to pop up. It will send that message when an open circuit fault is detected on the trailer itself, or if there's a corroded or bad connector.

 

I will get a new batter tomorrow , I replaced the brakeaway switch and went through the fuse box under the trailer. I did find some questionable connections that I addressed . I put a meter on the the batter and it had 12.6 v.i also ran new wire to batter.

 

If you can test the battery first that will tell you if it's good or not, rather than buying one if the current battery is fine. 12.6v is still a good charge, but a battery tester can really tell you yes or no. Some auto parts stores might be able to test it for you too.


Other than that check all your trailer wiring. Ohm out suspect wiring to see if you still have some lingering issues.

 

also check the connections to the axle/brakes
some trailer manufacturers use the crappy scotch tap connectors that corrode and fall apart over time.

 

Don't forget to check the ground connections.

 

X2! Mine had the same issue. Put a new ground wire on it and VOILA! Works great now.

 

X2......whenever I have electrical issues with a trailer, this is always the FIRST thing I make sure of. A poor ground can make things appear to be totally wonkers!

 

New ground and all is good!!
Thanks for the help.
I was freezing my a££ off last night and needed to walk away from it.
It started to snow last night and still is now but I just put a new ground to the frame out side the fuse box . I went over every connection and found a lot of corroded connectors (5) and found one electric break wasn't even hooked up . So... All good going to safety lane now.

 

ditto....move this up on the priority list