I just had the dealer install the Factory Trailer Brake Controller on my 09 5.4 Supercab. It looks great, it works great, well worth the extra money over the "knee banger" type. My question is... they did not install the relay that came in the bag with the harness for an aftermarket controller. I was under the impression the relay is necessary so the truck will charge the RV battery while in transit, do I need to install this relay ??? or is it not necessary because its the factory controller.

 

Yes i needed to install that to get power to charge my trailer brakes and internal lights.

 

Ditto - needed to install the relay myself also.

 

Hey, I just stumbled across this thread. So the relay that came in the glove box needs to be hooked up to ensure the trailer lights work? I am somewhat confused. The integrated brake controller is not fully hooked up at the factory? I would appreciate more details on this. Thanks.

 

It is not so the lights will work. I believe it completes a connection so that the battery on your RV with charge from the truck voltage when its hooked up. I guess some people dont want this function to be in tact, therefore they dont install it at the factory or at the dealer with the install. I thought it rather odd myself, thats why I started this thread..

 

Okay. I have a car hauler and the only battery I have is for the 'break-away' setup. I imagine this works in a simliar manner (from a charging perspective) as your RV battery. I'll hook mine up this weekend; thanks.

 

Yes - that relay will allow your break-away battery to charge.

 

Had mine installed today. $318.71 out the door with parts and labor from my Ford Dealership.

 

So, how do you hook up the relay?

 

Just push it into the designated slot in the fuse box. Just like you would install a fuse.

 

Thanks

 

So, to clarify...those of us who's trucks came with the factory Integrated trailer control should have been given a relay in the glove box? I don't recall getting one. I believe I did get a length of trailer harness but don't recall a relay?

Once installed the relay will allow you to charge an aux battery (trailer, etc.) but it would also stand to reason that the aux battery would feed off the trucks battery which <could> result in a no start situation if you used the trailer accessories too long without starting the truck?

 

my relay was in the bag with the trailer harness

 

Just to review...You should have gotten a bag containing a small wiring harness (which you don't need), the relay, a Fuse, and instructions.

 

Yup