New (old) TV--4-pin to 7-pin question

[larrylifelines]

After years of depending on others for my TV, I bought an 18-year-old Ford Explorer this week. Has a 2" receiver, so towing is no problem. But the car has a flat, 4-pin wiring harness, which I need to adapt to my TM's 7-pin. I bought an adapter, and tried it out. Very weak on the turn signals, and haven't tested other functions yet.
What do I lose in going from 7- to 4-pin? Braking? That wouldn't be cool. Appreciate any advice.

Ken Franklin
Hudson Valley, NY
2720SL

[Bill]

Ken -

The 4-pin connector is intended for lightweight utility trailers. It is missing some of the functions that a camping trailer such as a TM requires.

The 4-pin connector carries 3 circuits plus ground. The 7-pin connector carries 6 circuits plus ground. The circuits are these:

. Connector. . . . . . . 7 pin . 4 pin
1. Left turn/stop . . . X . . . . X
2. Right turn/stop. . . X . . . . X
3. Running lights. . . . X . . . . X
4. Trlr brakes. . . . . . X
5. Trlr 12v charge. . . X
6. Trlr backup lghts. . X
7. Ground . . . . . . . . X . . . . X

As you can see, the 7 pin connector carries three circuits that the 4-pin connector doesn't have. These are the trailer brakes, trailer backup lights, and the 12 VDC trailer battery charge line. There is no way for an adapter to create these functions. You must add wiring from the engine compartment area to the rear bumper, and mount a 7-pin connector there.

Note that if you go to an on-line RV parts site such as e-trailer.com, you can find what they call a 4-pin to 7-pin converter. This is a simple device that simply picks up the 4 wires from your tow vehicle's 4-pin connector, and routes them to the proper pins of a 7-pin connector. In other words, they do a mechanical conversion - you can plug the TM 7-pin connector into them. But they do not create the missing functions.

Bill

[HoMiPa]

etrailer is probably the best place to start. They have everything you need, and are very helpful. To start you can enter your vehicle make/model/year, and the website will bring up the correct parts for you. For example, when I ordered the break system for my '88 Bronco, this is the wiring kit I ordered:

https://www.etrailer.com/faq-etbc7.aspx

It's easy enough to do yourself - a few hours, the correct tools, and you'll have your new-to-you vehicle wired for your TM.

[dr carver]

Ken,

Often the wiring harness already exists on the vehicle.
A quick check is to see if you have a plug under the dash (usually near the steering column) in the driver's position to attach a brake controller. If it is there, then there is probably a plug in the rear to attach a 7-pin connector and positions in the fuse panel for fuses and a relay for brakes and trailer battery.

If not, then you need to use the kit such as the one from etrailer.

[Bill]

Originally Posted by HoMiPa

etrailer is probably the best place to start. They have everything you need, and are very helpful. To start you can enter your vehicle make/model/year, and the website will bring up the correct parts for you. For example, when I ordered the break system for my '88 Bronco, this is the wiring kit I ordered:

https://www.etrailer.com/faq-etbc7.aspx

It's easy enough to do yourself - a few hours, the correct tools, and you'll have your new-to-you vehicle wired for your TM.

You're right, Holly. The kit in your link is not the simple 4-to-7 mechanical converter that I described above, which many owners think will somehow provide the needed trailer functions such as braking. To use the kit you described, and assuming your tow vehicle does not already have the wiring described by DR CARVER, e-trailer makes it clear that you will have to add wiring to your tow vehicle

Conclusion? When you find a 4-to-7-pin converter offered on line, be sure you understand which kind is being offered.

Bill

[tentcamper]

I would just get the 7-pin connector that is ready for a 4 - pin flat connector from the TV to plug-in. Most also have a 4 - pin connector for the trailer on them. Then you only have to wire up the 3 other wires.

But it sounds like you have a poor ground.

[bonusvalue]

I bought a 7 pin connector for my tow vehicle that uses the 4 pin connector at etrailer.com. Only 3 wires to connect to finish the job. Very simple and I am not a electrician.