Just bought a small travel trailer and need to wire a 7 prong socket, lights, electric brakes and battery charging for the truck. What do I need besides the socket? How to wire. Thanks. '99 Explorer AWD 5.0 Eddie Bauer

 

You need a trailer brake controller and, if your Explorer has a pre-wired plug for the trailer brake controller, you will also need the harness to take advantage of the pre-wired connector. Then you need to find the pre-wired connector which could be taped up above the accelerator pedal or taped above the glove box. There are other threads that detail where to find the plug and what it looks like so I won't go in that detail here.

If your truck is not pre-wired, then you will also need to wire to the brake pedal switch and run a wire from the brake controller back to the 7-pin connector.

There may already be a round connector below one of the taillights that will have the trailer wiring signals present which would make installing the 7-pin socket easier, otherwise you'll need to tap in to the factory taillight wiring, solder the connections, and seal the splices from the elements. DO NOT use the "Scotch-Lok" connectors that are so common. Those are not intended for splices exposed to the elements and there's a VERY high liklihood they will cause other lighting issues in the future due to corrosion.

You don't mention if your Explorer has a receiver hitch so if not, you'll need one of those that is properly rated for your travel trailer. And, depending on the length and tongue weight of your travel trailer, you may also need a weight-distribution hitch with anti-sway.

-Rod

 

Thanks shorod. I figured I'd need a brake controller, if I wanted to use the brakes, and can probably install that with the directions that come with it. What I need to know is where to find the power wire and brake wire to the 7 pin socket. There is a flat 4 connector on the truck that I jerry rigged to tow the trailer home so the lights are no problem. I had to tow it over 100 miles home and the brakes were no problem but it swayed a bit when a big rig sped by me. I drove a slide-in camper for over 30 years and that swayed when a truck passed me too so I guess I'll get used to that. Yes it has a receiver hitch. I tow a boat that weighs more than the camping trailer with no problem and it doesn't have brakes. I just read GA law and since my trailer is under 3000 lbs it's not required to have brakes. But I would like to charge the trailer battery when moving. Do I just get 12 v from the battery and how do I keep from discharging the truck battery when it's not running? Does the converter in the trailer do that? I wouldn't use those cheezy connectors for anything but thanks for reminding me.

 

You can check for a round connector under the rear taillights (I don't recall which one they are typically under). If the plug is there and has never been used before, there will be a rubber cap in it to keep junk out. Pull out the rubber cap and plug in a trailer wiring adapter harness available from most local auto parts stores. That should have the trailer power wire in it. If such a connector is not already present in your truck, then you will need to run a fused line from your battery. And the camper will be able to pull from the truck battery if there is a draw from the camper. There's no smarts in the converter that will shut off the camper draw. However, once the battery in the camper is charged there shouldn't be a load from the trailer on your truck. You might consider a solar battery maintainer for your camper when it's stored to keep the battery topped off.

Yeah, if your camper is under 3000 lbs it probably doesn't even have trailer brakes, so in that case there's no need to worry about a brake controller at this point. It sounds like the money you save on the brake controller should be put to use buying an anti-sway controller though.

-Rod

 

On vehicles with the factory 7 pin plug the trailer battery charge wire comes from a relay in the fusebox that is only on while vehicle is on. Trailer battery will only charge when vehicle is runing and the camper will not discharge vehicle battery when sitting with truck shut off.

Also with factory wiring the trailer turn and stop lights have their own fuses.

Kevin

 

There is a round plug under the driver's side tail light but it only has 4 connectors and the flat 4 socket is plugged into it. I will run a power wire through a relay to the socket when I get it. What size wire do I run, 12ga? Thanks guys.

 

Is the relay just so the 12V power line only has power with the vehicle running? Assuming so, don't forget the appropriately sized fuse as well. From the factory Ford used a 30A fuse. A 12 gauge wire would be about right (and also what Ford used), resulting in about a 1.2V drop at full 30A load. I'd suggest seeing what the current rating is of the socket and size the fuse accordingly. The factory wiring stepped down to 14 ga near the connector.

-Rod

 

That's what the relay is for. I have a 35A fuse and bought 25' of 12/3 cable. I ran 2 wires for the power and the other for the brakes when I get the controller. I'm at a loss where to get a switched hot wire for the relay. Without using the coil wire do you know any handy wires?

 

I might be tempted to tap into the wire that comes off the trailer tow park lamps relay. Then the only time your added relay would let the camper battery charge would be when you have the park lights or headlights on, which I usually have on when towing anyways. I guess that could backfire though if you accidently left the lights on.

Honestly I don't know on the Explorer. I never needed battery charge with my 1991 or 2002. On my 2004 Expedition the relay socket was already wired and the orange camper charge wire was already ran back near the gas tank. I just had to buy an OEM rear harness that had the 7 pin wires in it to upgrade from my 4 pin wire harness. I also picked up the 4 wire brake controller kit that includes the needed relays to upgrade to the towing package.

Kevin

 

You mention 12/3 wire. That sounds like how home wiring is specified. You didn't buy home Romex wire, did you?

Are you planning to place the relay under the hood, near the battery? If so, there are several fuses in the battery junction box that are only hot with the key in the Ignition/Start/Run positions. I would suggest using a fuse tap on the protected side of the fuse to power the relay coil.

-Rod

 

Thanks, I didn't know what a "fuse tap" was until I googled it. No I didn't use Romex I used extension cord wire. I'll have to get my meter and check which fuse is switched.