My 2015 Lariat has the Max tow package on it, is there anyway I can tell if it is charging the battery for my brake away switch in my enclosed trailer? I have started by truck and checked all contacts on my 7 way connector. the only power I can get is signal lights, running lights and of course brake lights. When all is shut off I have no power coming out of the 7 way connector at all with engine running. I know my 2012 had to have a fuse installed to get it to charge but I can't figure this one out. Surely this doesn't just put out power when the computer detects the trailer is hooked up.

 

You need to make sure you are getting power to the battery of the break away battery when hooked up to the truck. Simply remove the battery, get a multimeter or a small 12v light and test the leads that connect to the break away battery with the trailer attached to the truck and with the truck's engine running. If you get 12-14v on the multimeter or the light lights up, you are good. If it does not, then it means the battery is not charging. After confirming this, you will then want to re-attach the battery. I suggest reattaching the battery while the trailer is disconnected from the truck or by turning the truck off.

Your truck (or any properly wired 7 pin RV style plug) should be powering/charging the battery from pins #1 and #4. Pin number 1 is the ground, and pin number 4 is the positive aux (it can also be used to power items like radios, lights, and other accessories inside of the trailer as well).

Here is a pin out of the 7 pin RV style on the truck:



That Orange Auxiliary pin is for reverse lights, which many trailers omit for some strange reason. In which, I think should be a lawful requirement to have reverse lights on trailers as well, but that is just me.

Always test your break away system by pulling the plunger and seeing if the trailer moves or jack it up and see if the wheels turn. If they do move, then it is either not working, OR you need to adjust your trailer brake shoes if they are not self-adjusting. Or else the battery is dead. Just like any other 12v battery, you can bring it in and get it tested. If it fails to test out, you need to get a new one. Most dedicated battery retailers will have them, if not they can order it. Or you can order one online. Normally these batteries are gel filled non-serviceable non-spill able batteries and last typically 3-7 years depending on quality of components and what environment they are subjected to, as well as charging and usage conditions.

Any other condition outside of this is going to be either a grounding issue/wiring issue, which you will then have to troubleshoot or in some circumstances rewire. I've seen in some extreme (poor maintenance/left outside) circumstances, the brakes rust out so bad, the windings in the electromagnets fail.

On my trailer break away system on my dual axle car trailer that I own, it has charging and testing info... I think every trailer break away system should have these basic features for safety!

It's a Hopkins.

If you don't like yours, just cut the old one out, splice in the new one, and call it a day.

Here's a pic:




Hopkins Break-Away System

And as always..... if this is above your head... take it to registered shop that deals with trailers.

 

Good info thanks one question I had was with the truck running why is there no power coming out of the plug. Isn't the the first thing I should have is 12 v coming out of the power wire? Just asking this before I start taking out batteries and breakaway switches.

 

Yes, there should be 12v coming out of that pin 4 when the truck is running.

If you are not getting 12v coming out of pin 4, then there is something wrong with the wiring on the truck, you blew a fuse, or a relay is not working or missing.

I've heard rumors that on certain trucks that you need to program in a trailer on the display cluster in order for it to activate.

On my truck, it is a '07, so it isn't fancy by any means. As soon as I turn the ignition past the interlock (run/on), it starts supplying power to the 12v pin 4 immediately.

 

I will check with the dealer tomorrow. As mentioned on my 2012 I had to install a relay in the fuse box. But did as dealer when I bought the truck that question they said no. Now that was a sales person though. I am thinking I may have to do the same on this one. Also as mentioned before I have nothing coming out the 12v feed.Thanks for all the great info.

 

Fact, not just a rumor. No trailer connected, no juice.

 

That is what I was thinking with these trucks no connection no power to the 12 volt pin. Although power still shows up at the signals and running lights. Maybe the only way to tell is at the battery like ManualF150 said.

 

It certainly cannot hurt to take the battery out quick, and test it.

If it still isn't working, I suggest taking it to the dealer and have them quickly test it. They usually have a dummy test plug that goes in there with a series of LEDs that show what is working and what is not. I've got a 4 pin flat, 6 pin round, and a 7 pin RV round. I keep them in my toolbox just in case.

To test your trailer, you can do one of two things... get a 12v battery (even the one from the trailer break away will work), and get one wire for the ground (-) and the other for the positive and go through each pin and check to see what happens. The other option is go to a shop that specifically works on trailers, and they have a battery operated trailer light/brake tester that can act as if it was connected to your truck and test all the functions of your trailer automatically.

Or you can do what I did, and build your own trailer tester.... but that is beyond the scope of this.

 

You know you remind me of something that we did before. A buddy does have a set of lights he made up just for that purpose to test the plugs. He use to install trailer hitches and I think he still has that set up. I will check it out thanks.